NAF International Working Paper Series Year 2013 paper n. 13/03 Early crop growth and yield responses of maize (Zea mays) to biochar applied on soil WILBERT TIGERE MUTEZO Department of Agriculture and natural resources Faculty of Agriculture Africa University P.O Box 1320 The online version of this paper can be found at: http://economia.unipv.it/naf/
50
Embed
Early crop growth and yield responses of maize ( Zea …economia.unipv.it/naf/Working_paper/WorkingPaper/gab/Mutezo.pdfEarly crop growth and yield responses of maize ( Zea mays ) ...
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
NAF
International Working Paper Series
Year 2013 paper n. 13/03
Early crop growth and yield responses of maize (Zea mays) to biochar applied on soil
WILBERT TIGERE MUTEZO
Department of Agriculture and natural resources
Faculty of Agriculture
Africa University
P.O Box 1320
The online version of this paper can be found at: http://economia.unipv.it/naf/
Scientific Board
Maria Sassi (Editor) - University of Pavia
Johann Kirsten (Co-editor)- University of Pretoria
Gero Carletto - The World Bank
Piero Conforti - Food and Agriculture Organization of the United Nations
Marco Cavalcante - United Nations World Food Programme
Luc de Haese - Gent University
Stefano Farolfi - Cirad - Joint Research Unit G-Eau University of Pretoria
Ilaria Firmian -IFAD
Mohamed Babekir Elgali – University of Gezira
Firmino G. Mucavele - Universidade Eduardo Mondlane
Michele Nardella - International Cocoa Organization
Nick Vink - University of Stellenbosch
Alessandro Zanotta - Delegation of the European Commission to Zambia
Copyright @ Sassi Maria ed. Pavia -IT [email protected] ISBN 978-88-96189-13-9
CHAPTER 1
INTRODUCTION
1.1. Background of Study
Maize is the staple food in Zimbabwe which makes it a very important crop. However
average yields have been decreasing very much .As an example of differences in production
systems, the average white maize yield in Zimbabwe on large-scale commercial farms
averages over 4 tons per hectare, compared with around 1 ton per hectare in the small-scale
commercial and subsistence sectors. Much of that difference is the result of differences in
moisture regime and soil quality, but part would remain even if these latter factors were
controlled. Total maize output of over 2 million tones in the year 2000 was achieved. Since
then production fell rapidly to less than half of Zimbabwe’s requirements indicating a high
degree of food insecurity and an obvious lack of production self-sufficiency.
In some years the situation was worsened by rainfall deficits. In the year 2010 the estimate
for total national maize output was expected at around 400,000 tonnes. This output is about
20% of that required to meet national demand for this commodity (Cfuzim, 2011). The
reduction of maize yields is a result of reduced fertilizer application rates and nitrogen use
efficiency. There is reduced mineral availability as a result of reduced cation exchange
capacity in degraded soils. These soils have low pH levels and result in increases nutrient loss
especially nitrogen through leaching. The soils are generally becoming sandy with reduced
organic matter content.
Biochar application helps farmers in several ways: less fertilizer is needed because biochar
absorbs and slowly releases nutrients to plants; biochar improves soil moisture retention and
conserves water, securing the crops against drought; farmers spend less on seeds as
emergence percentages increases; biochar reduces the methane emissions from paddy fields
and farm yard manures; it increases the soil microbes and other soil-life density; it lessens the
hardening of soils; it supports better growth of roots and helps in reclaiming degraded soils.
Another advantage of biochar is that it can be used in all types of agricultural systems
There are several reasons to expect that biochar might decrease the possibility of nutrient
leaching in soils, and enhanced nutrient cycling has been cited in various field studies for
positive impacts on yield. However, very few studies have demonstrated the effect or
attempted to quantitatively describe the mechanism. In general, the mineral and organic
fractions of soil can both contribute to overall CEC, which affects the ability for soils to
buffer periodic flushes of ammonium that result from application of chemical fertilizers or
manures, or bursts of organic matter mineralization during favorable, seasonal conditions.
The adsorption of ammonium ions is a relatively loose association that does not necessarily
prevent plant acquisition, yet greatly mitigates the potential for leaching loss and the diffuse
pollution issues of drinking water quality and eutrophication of water bodies.
Since considerable fossil energy is required to fix nitrogen into fertilizer, a low ratio of
fertilizer nitrogen application to crop nitrogen uptake can impact the overall carbon balance
of agricultural activities. Higher fertilizer use efficiency should lead to a lower fertilizer
requirement per unit yield and usually lower nitrous oxide emission. Only certain mineral
constituents of soil contribute to CEC on account of abundance, and hence surface area, and
mineralogy, with certain types of clay being most important.
On a mass basis the exchange capacity of soil organic matter may be greater than for any clay
(and up to 50 times greater), but it is a relatively small proportion of soil mass in most
agricultural situations, particularly under tropical conditions. Given these factors, heavy
textured soils under climates that favour higher levels of organic matter show the highest
contributions of organic matter – about one-third – to total soil CEC (Stevenson, 1982).
Since mineralisation of organic matter is a major source of ammonium release in soil,
attempts to raise soil organic matter by increasing rates of input may not decrease – and can
potentially increase – leaching losses. In addition to the chemical stabilisation of nutrients,
the physical structure of soil determines its capacity to hold water, and hence soil nutrients in
solution.
There are several reasons to expect that biochar might modify leaching potential in soils.
Available evidence suggests that on a mass basis, the intrinsic CEC of biochar is consistently
higher than that of whole soil, clays or soil organic matter. An analogy may be drawn to the
extreme CEC of activated carbon, which is relevant to its function as a sorption medium for
decolourisation and decontamination. Since secondary thermal treatment of charcoal is one
means of carbon activation, it is not surprising that the process parameters impact the CEC of
primary biochar products with temperature increasing this property (Gaskin, 2007).
This is a function of both enhanced specific surface area and the abundance of carboxyl
carbon groups that they display. The indirect affect of biochar that may result from its
modification of soil pH has not yet been included in most studies by, for example, applying
lime to the control soil. Whilst determination of CEC and water release curves in
homogeneous materials such as biochar should be straightforward, it is more complex to
quantitatively determine the contribution of biochar once added to soil. Furthermore, the
observation that CEC of biochar may develop over time through both abiotic and biotic
modification of its surfaces (Cheng et al., 2006) implies that in order to develop a predictive,
quantitative understanding, methods to recover aged biochar from soil is required.
Information on the CEC of pyrolysis products is limited mainly by the availability of
materials produced from a sufficiently diverse range of feedstock under different production
conditions. Information on the CEC of char naturally present in soils is limited by isolation
methods, so available studies tend to rely on a comparison of whole soils amended and non-
amended with biochar (Lehmann, 2003; Liang, 2006). The second mechanism for mitigation
of leaching relates to the physical retention of soil water, which may be enhanced by biochar
in coarse-textured soils and any indirect effect of biochar on the accumulation of soil organic
matter.
The inherent stability of biochar confers a distinction between the CEC benefits that are
possible compared to other soil organic matter; importantly there is no immediate constraint
to the level that can be attained by repeated addition, so in principal this capacity could be
incrementally enhanced. Provided that biochar is biologically stable, the benefit of higher
CEC may be obtained without the risk of contributing to seasonal flushes of nitrate. The
possible contributions of a modified soil water dynamics and CEC to the apparent effects of
biochar on nitrous oxide emission are evident. In addition to mitigating greenhouse gases
emissions, limiting gaseous nitrogen loss can be relevant to crop fertiliser requirement. A
beneficial impact of biochar on the plant-available phosphorus has been observed in soils
enriched with biochar, which in contrast to ammonium, is not a characteristic generally
associated with soil organic matter (Lehmann, 2007b; Steiner et al., 2007). In the context of
nutrient availability, the impact of biochar addition on pH may be important.
A central part of any strategy for expanding the number of smallholders who use inorganic
fertiliser will be to determine how to make the best use of limited amounts of fertiliser that a
typical is able to purchase. Increasing fertiliser-use efficiency will require a significant shift
in thinking for both researchers and policy makers in Africa. For instance, Zimbabwe has
more than a fifty-year history of agricultural research on inorganic fertilisers, but much of
this work was geared towards users who could afford relatively large quantities of fertiliser
(large commercial farms and growers of cash crops). Since independence in 1980, a great
deal of work has examined the appropriateness of types, amounts, timing, and placement of
inorganic fertilisers for food crops by smallholders, yet recommendations for inorganic
fertiliser have not given sufficient attention to the cash constraints and risk faced by resource-
poor farmers in marginal areas. Of the 325 of farmers in Zimbabwe who followed the
fertiliser recommendations for maize crop in the near-average season of 1990/91, 48% failed
to recover the value of the fertiliser (Page and Chonyera, 19994).
Additions of soil micronutrients can improve the yield response to macronutrients (N and P)
on deficient soils. Nutrients such as Zn, B, S and Mg can often be included relatively cheaply
in existing fertiliser blends, when targeted deficient soils, these nutrients can dramatically
improve fertiliser-use efficiency and crop profitability. There is evidence that the most
promising route to improving inorganic fertiliser efficiency in cropping systems is by adding
small amounts of high-quality organic matter to tropical soils (Ladd and Amato 1985; Snapp,
1995). High-quality organic manures (possessing a narrow C/N ratio and low percentage of
lignin) provide readily available N, energy (carbon), and nutrients to the soil ecosystem, and
they build soil fertility and structure over the long term. Their use will increase soil microbial
activity and nutrient cycling and reduce nutrient loss from leaching and denitrification (De
Ruiter et al. 1993; Snapp, 1995).
2.7 Soil organic matter and climate change
In order to understand the potential significance of carbon in soil in the form of biochar, its
characteristics and dynamics should be compared to those of the remaining soil organic
matter, which accounts for most of the carbon that exists in soil (the exception being
calcareous soils which contain stocks of inorganic carbon in carbonate minerals). Depending
on land-use and climate, most soils contain up to approximately 100 t/ha carbon as organic
matter. Peat soils, though, comprise mainly organic matter and contain much more carbon on
a per unit area basis. It is increasingly recognised, however, that a greater proportion of the
total carbon may comprise an accumulated store of the products from burning or fire
(Skjemstad et al., 2004a), and that this has implications for the response of the wider soil
carbon pool to climate change (Skjemstad et al., 1999; Lehmann et al., 2008).
Modelling indicates that about 90% of the organic matter present in soils turns over on
decadal to centennial timescales (Coleman et al., 1996; McGill, 1996). Most organic matter
in soil is derived from plant roots, plant debris and microbially degraded substances. The
presence of soil organic matter is important for a range of useful soil properties, which has
been comprehensively reviewed by Krull (2004). The process of microbial energy acquisition
(and concomitant carbon dioxide release) from substrate is accompanied by a release of
various nutrient elements, which may be conserved in the soil in microbial biomass or the
particulate residues of substrate decomposition.
A portion of certain nutrients may also be released in soluble form, and a fraction may be lost
from the soil through leaching or run-off; which is essential to crop nutrition. This is
particularly the case where external nutrient provision (from fertiliser or manure) is limited or
absent. Overall, a balance slowly develops between the rate of carbon addition and the
emission of carbon dioxide, which are specific to the land-use and environmental conditions.
The amount of organic matter maintained once this balance is reached, depends on its
average rate of turnover. To date there have been few means proposed that permit
manipulation of this rate, so that soil carbon can be permanently increased. Beyond simply
increasing the amount of external organic matter inputs (Smith et al., 2000), the main
strategies are to disturb the soil less by using less intensive tillage or zero tillage (Lal, 1997;
Smith et al., 1998), or by selecting particularly recalcitrant, lignin-rich amendments (Palm et
al., 2001).
Although conversion to no-till soil management has been widely promoted as an approach to
enhance soil organic matter as well as to control erosion and conserve water, the main effect
appears to be a vertical re-distribution of organic matter, and an increase toward the surface
more or less matched by a corresponding depletion at depth (Bhogal et al., 2007; Blanco-
Canqui et al., 2008). Nonetheless, the Chicago Climate Exchange includes a specification for
‘conservation tillage’ amongst its Carbon Financial Instruments for carbon sequestration and
thus a precedent for the active engagement of farming in the carbon market
18 (<http://www.chicagoclimatex.com/>).
Managing decomposition in soil by manipulating the quality of inputs has been explored
extensively in tropical environments where decay is rapid (Palm, 2001). But simply altering
the composition of soil inputs has only a relatively minor impact on the composition and
long-term fate of the small portion that is stabilized, with incorporation and repeated
decomposition inside the dominant, slow turnover pool. Thus the main emphasis in the
sequestration debate has been focused on increasing soil carbon by increasing organic matter
additions in the form of straw or other crop residues, and from external sources such as
manures and a range of organic wastes: sewage sludge, municipal compost, paper waste, and
so on. Although there is a large amount of such material available, the quantity is relatively
small compared with the total flux through soil, particularly the size of the global soil carbon
pool. When a soil is at equilibrium, only about 10% of the carbon added to soil is stabilized
for more than one year. During a transition, progress to new equilibrium is slow, with the
annual increase being small relative to the carbon invested. As equilibrium is approached the
annual rate of accumulation decreases, and once reached, the new level of input has to be
sustained simply to maintain it.
Furthermore, the capacity to store organic matter is ultimately limited (with the capacity
varying with soil type, water regime and climatic factors); thus the improvement in carbon
storage that is possible for each incremental increase in input (Stewart et al., 2007; Gulde et
al., 2008). As well as added carbon being rapidly re-emitted into the atmosphere, carbon is
lost in the formation of soil organic matter through digestion in the animal gut or oxidation in
conversion to compost. The level of carbon sequestration or offset that could be realised
through an alternative use of these materials, including fossil fuel substitution, must be
considered when assessing the efficacy of these strategies from the perspective of climate
mitigation alone (Schlesinger, 2000). For example, the carbon cost of producing N fertiliser is
relevant when proposing to increase soil carbon storage indirectly through enhanced plant
growth (Schlesinger, 2000).In the context of the interventions generically referred to as
‘management options’, important soil physical benefits may be gained by accumulating soil
organic matter (Janzen, 2006).
However, these must be balanced against the opportunity costs, the forgone benefits that
might arise from its breakdown and turnover, most importantly the release of crop nutrients
(Janzen, 2006). In general, however, any form of organic matter added to the soil degrades
resulting relatively quickly in carbon dioxide emission.
References Chan, K. et al., 2008. Using poultry litter biochars as soil amendments. Soil Research, 46(5),
pp.437–444.
Cushion, E., Whiteman, A. & Dieterle, G., 2010. Bioenergy development: issues and impacts for poverty and natural resource management, World Bank Publications.
Fruth, D.A. & Ponzi, J.A., 2010. Environmental Law: Adjusting Carbon Management Policies to Encourage Renewable, Net-Negative Projects such as Biochar Sequestration. Wm. Mitchell L. Rev., 36, pp.992–5249.
Irwin, M.P.S., 1981. The birds of Zimbabwe, Quest Pub.
Jeffery, M.I., 2011. CLIMATE CHANGE MITIGATION AND ADAPTATION POLICY OPTIONS: REDUCING AUSTRALIA’S DEPENDENCE ON COAL, NATURAL GAS, AND OTHER NONRENEWABLE ENERGY RESOURCES. Ind. Int’l & Comp. L. Rev., 21, pp.447–509.
Lehmann, J., Gaunt, J. & Rondon, M., 2006. Bio-char Sequestration in Terrestrial Ecosystems – A Review. Mitigation and Adaptation Strategies for Global Change, 11(2), pp.395–419.
Messenger, S.P., 2009. BIOCHAR: A Cost Benefit Analysis in the Scottish Whisky Industry, VDM Verlag.
Novak, J.M. et al., 2009. Impact of biochar amendment on fertility of a southeastern Coastal Plain soil. Soil Science, 174(2), p.105.
Nyamapfene, K.W., 1991. The soils of Zimbabwe, Nehanda Publishers.
Sparks, D.L., 2011. Advances in Agronomy, Academic Press.
Steinbeiss, S., Gleixner, G. & Antonietti, M., 2009. Effect of biochar amendment on soil carbon balance and soil microbial activity. Soil Biology and Biochemistry, 41(6), pp.1301–1310.
CHAPTER THREE
THE EFFECTS OF SEWAGE SLUDGE BIOCHAR ON THE SEEDLING GROWTH AND EMERGENCE OF MAIZE IN THE RED SOILS FERSIALLITIC 5E OF ZIMBABWE 3.1. INTRODUCTION Maize can be grown on a wide variety of soils, but performs best on well-drained, well-
aerated, deep warm loams and silt loams containing adequate organic matter and well
supplied with available nutrients. Although it grows on a wide range of soils, it does not yield
well on poor sandy soils, except with heavy application of fertilisers on heavy clay soils, deep
cultivation and ridging is necessary to improve drainage. Maize can be successfully grown on
soils with pH of 5.0-7.0 but a moderately acid environment of pH 6.0-7.0 is optimum.
Outside this range results in nutrient deficiency and mineral toxicity. High yields are obtained
from optimum plant population with appropriate soil fertility and adequate moisture. There is
need to examine ways to increase early seedling growth rate so as to improve on the
emergence success rate hence the yield increase. Biochar improves the physical conditions
around the crop-root zone and enhances crop production (Shinogi et al., 2003). For example,
5% charcoal application per weight doubles the hydraulic conductivity of loam soil. This
effect is dependent on soil type and can last for years. The amount of generated wastewater
sludge has increased dramatically due to urbanisation and industrialisation and is expected to
continue in the future.
Pyrolysis is one of the options for managing wastewater sludge where biochar produced
during pyrolysis can be applied as a soil amendment. Biochar from sewage sludge contain
phosphorus (P) and potassium (K) with citric type and these are essential nutrients for crops.
Land application of municipal sludge (biosolids) is a growing practice in agriculture (Bloom,
1997). Therefore, biochar from sludge can replace chemical fertiliser. However, nitrogen in
biochar a major nutrient for crops is not easy to be used by crops (Chen et al., 2007).
There is, however, considerable variation in plant and soil responses to biochar that cannot be
evaluated in a single study and may be lost in the overall message of a literature review.
Source of material and pyrolysis conditions (especially temperature) introduce significant
variation in the structure, nutrient content, pH, and phenolic content of the biochar products
(Novak et al., 2009a). Interactions with climate, soil type (texture, chemistry, hydrology)
(Tryon, 1948; van Zwieten et al., 2010a), and fertilization status (van Zwieten et al., 2010b;
Haefele et al., 2011) can also contribute to uncertainty in how biochar interacts with
organisms.
Sewage sludge biochar has been shown to increase plant productivity and yield though
several mechanisms. Soil physical conditions change with biochar; its dark colour alters
thermal dynamics and facilitates rapid germination, allowing more time for growth compared
with controls. Biochar can also improve soil water-holding capacity (Laird et al., 2010b),
facilitating seedling biomass gain (Kammann et al., 2011). Plant growth responses can also
be altered by biochar-induced changes in soil nutrient conditions, particularly the cycling of P
and K (Taghizadeh-Toosi et al., 2012). In the plant tissue K concentration and soil P and K
increased following biochar application.
These nutrients may be directly introduced to the soil through labile organic compounds
associated with biochar and become available as these compounds weather (Topoliantz &
Ponge, 2005; Yamato et al., 2006). This effect, however, depends on the production variables
of the biochar (Hass et al., 2012), and is short lived, as the nutrients are used by plants and/or
are leached from the soil (Steiner et al., 2007; Major et al., 2010). Biochar-type materials
have been reported to stimulate root growth for some time (Breazeale, 1906). The very
different properties of biochar in comparison to surrounding soil in most known cases
improved root growth. In fact, roots may even grow into biochar pores (Lehman et al., 2003).
Makoto et al. (2010) showed not only a significant increase in root biomass (47%) but also
root tip number (64%) increased within a layer of char from a forest fire with larch twigs,
birch twigs, and shoots of dwarf bamboo buried in a dystric Cambisol.
The number of storage roots of asparagus also increased with coconut biochar additions to
tropical soil (Matsubara et al., 2002). Germination and rooting of fir embryos (Abies
numidica) significantly increased from 10 to 20% without additions to 32-80% of embryos
when activated carbon was added to various growth media (Vookova and Kormutak, 2001).
Therefore, not only abundance, but also growth behaviour of roots may change in response to
the presence of biochar.
Soil compaction can result in yield reductions due to decrease in seedling germination, root
and plant growth, and nutrient uptake. The objective of this study was to look at the effects of
sewage sludge biochar on the emergence of maize.
3.2. MATERIALS AND METHODS
3.2.1. Site description
The experiment was conducted in the field at Africa University (AU) farm. The soil at AU is
a red Fersiallitic 5E soil under Zimbabwe soil classification system. The soils are strongly
sandy clay loamy soils (Nyamapfene, 1991). The average annual temperature is 19 °C,
surprisingly low for its moderate altitude (about the same as Harare which is 360 metres
higher.) This is due to its sheltered position against the mountain ridge of Cecil Kop which
encourages cool breezes from lower altitude to the east and south. The coldest month is July
(minimum 6 °C and maximum 20 °C) and the hottest month is January (minimum 16 °C and
maximum 26 °C), although as in much of Zimbabwe, October has the hottest days (28 °C).
The annual rainfall is 818 mm. Rain falls mostly in the months December to February
although heavy showers are possible before and after this period. The wettest month on
record was January 1926 which received 580 mm while January 1991 received only 24 mm
(Irwin, 1981).
Description of the crop varieties to be used.
CROP VARIETY General Comments MAIZE SC403 SC 403 is a very early white Maize Streak and Mottle
Viruses tolerant hybrid, with a relatively short, flinty ear and excellent yield stability over a range of environments with relatively slow dry down rate. It has outstanding drought tolerance with very good synchronization of silks. In numerous trials in communal areas over several seasons, SC 403 has performed very well under drought conditions. On average, SC 403 has a higher yield potential over SC 401. SC 403 has hard, very dense grain and has outstanding tolerance to both Diplodia and Furasium cob rots. SC 403 is widely recommended for harsh conditions where yields of less than 6t/ha are expected. It is also recommended for irrigation schemes an early Maize Streak Virus tolerant hybrid is required.
3.2.2. Experimental Design Five treatments were used:
1. 15 tons/ha biochar.
2. 15 tons/ha biochar and 300 kg/ha Compound D (7:14:7, N: P2O5:K2O) fertilizer.
3. 15 tons/ha biochar and 150kg/ha Compound D fertilizer.
4. 300kg/ha compound D fertilizer.
5. No amendment (control)
The biochar was thoroughly mixed with the soil and/ or the fertiliser before planting. The
amounts of biochar incorporated were calculated on the 20mm ploughing depth. Two
kilograms of soil were used in each separate treatment. Each treatment was replicated three
times. For each of the three replicates of each treatment, twenty seeds (cultivar Sc 403) were
distributed evenly and buried 15mm into the soil or soil mixture and left for six days at room
temperature (250C). For all the three replicates, coleoptiles length and weight, root length and
weight and seed weight were assessed.
After washing, seedlings were separated into coleoptiles, root and seed and then dried at 650C
for 48 hours before dry weights were recorded. The biochar is from Mutare city council
sewage and water treatment department.
3.2.3. Data analysis
The effect of biochar or biochar and compound D mixture on the physiology of maize
seedling growth were analysed using GenStat Release 7.2 DE. Where significant effects were
detected in the ANOVA (P=0.05), means were compared using least significant difference.
For data where no significant effects were observed, means and standard errors are presented.
3.3. RESULTS
There were significant difference on germination and emergence among treatments (P<0.05)
Table 1: Table shows the mean seed weight, coleoptiles length, coleoptiles weight, and root
length and weight and emergence percentage at seven days after planting for the five
treatments.
Treatment Seed
weight(g)
Coleoptiles
length(cm)
Coleoptiles
weight(g)
Root
length(cm)
Root
weight(g)
Emergence
% at 7 days
1 5.350a 9.767ac 0.4433a 21.40d 0.6433a 96.00a
2 6.473bc 10.800b 0.3883b 9.04a 0.1867b 70.00b
3 6.533c 9.867c 0.4000b 11.57b 0.6067a 99.33c
4 6.277bc 8.833d 0.1367c 11.17b 0.3900c 64.00d
5 6.140b 9.367ad 0.1400c 20.30c 0.7300d 82.00e
Columns with different letters shows means are significantly different (P<0.05)
Table 2: Table shows the correlation matrix for seed weight, coleoptiles length, Coleoptile
weight, and root length and weight and emergence percentage at seven days after planting for
Figure 1 below shows the differences in the coleptile length and root length for the five
treatments. This also confirms on the correlation of the two as given in the table 2 above of
the correlation matrix. The root length and coleoptile length are negatively correlated.
Figure 1: Figure shows the coleoptiles length and root length for the five treatments
0
5
10
15
20
25
trtnt 1 trtnt 2 trtnt 3 trnt 4 trtnt 5
coleoptile length
root length
Figure 2 below shows that seed weight is negatively correlated to coleoptile and root weight. Table 2 above also show the same from the correlation matrix.
Figure 2: Figure shows the treatment difference for seed weight, coleoptiles weight and root weight
Table 2 above shows that emergence percentage is positively correlated to all except for seed
weight alone. There is a correlation of nitrogen availability and crop emergence.
Figure 3: Figure shows germination percentages for the five treatments at seven days after
planting
0
1
2
3
4
5
6
7
trnt 1 trnt 2 trnt 3 trnt 4 trnt 5
seed weight
coleoptile weight
Root weight
0
20
40
60
80
100
120
trtnt 1 trtnt 2 trtnt 3 trtnt 4 trtnt 5
germination %
germination %
3.4. DISCUSION
Crop emergence was highest when biochar was applied with half the full fertiliser
recommendation as shown in figure 3 above. This was followed by biochar applied alone.
Surprisingly, the control emerged more than both the full fertiliser application without
biochar and full fertiliser application with biochar. Coleoptile lengths were highest in
treatments with biochar with full fertiliser application rate. This might have been caused by
high levels of nitrogen in the full fertiliser with biochar treatment. This will also confirm on
the ability of biochar to make nutrients readily available for crop uptake by increasing the
cation exchange capacity. High nitrogen levels around the seed will reduced seed germination
(Walter et al., 2003) as shown in figure 3 above. The seed act as the primary source of
nutrition before the crop is able to manufacture its own food by photosynthesis. Figure 2
shows that treatments with high seed weight showed a reduction in the coleptile and root
weight. This might suggest that there was interference between mineral availability in the soil
and hydrolysis of carbohydrates in the seed coat resulting in the negative correlation as
shown in table two above for root weight and coleptile length with seed weight.
The below-ground environment from which plants extract nutrients and water is highly
heterogeneous, both spatially and temporarily. For example, inorganic nitrogen
concentrations in the soil may range a 1000-fold over a distance of centimeters or over the
course of hours (Bloom, 1997b). Given such heterogeneity plants depend on various tropisms
(e.g. gravitropism, thigmotropism, hydrotropism and, perhaps even, chemotropism) to guide
root growth towards soil resources (Epstein and Bloom, 2005). The root length was smallest
in the treatment where full fertiliser without biochar applied. Walter et al. (2003) reported
that elongation of maize roots was faster in pure water than in nutrient solution containing
both NH4+ and N03
-. In this research the control also showed highest levels of root growth
that all other treatments with either fertiliser and/or biochar applied.
High accumulations of free NH4+ in tissues are toxic because they dissipate pH gradients in
the mitochondria and plastids (Epstein and Bloom, 2005). This might explain why the roots
grew very slowly in the full fertiliser application with biochar treatment. The roots
accumulated high levels of free NH4+ in the meristems confirming the ability of biochar to
make nutrients available in the soil solution for plant uptake when it is used together with
inorganic fertilizers.
Similar work with wheat showed interesting below ground biomass difference between 0.05
and 0.5% biochar compared to the control. The investment in root growth and allocation of
resources to roots was a major factor to emphasize nutrient acquisition and consequently
higher plant growth at the fertilised 0.05 and 0.5% biochar application levels. The unfertilised
0.05% biochar application level seems to have enhanced the root resource availability of the
wheat. At the fertilised 2.5% biochar, the root investment was higher than the control.
However, this did not translate into higher growth of plant mass. The reason could be that
biochar affected the physical structural properties of the soil system (Downie et al., 2009) by
increasing the bulk density, inhibiting root growth, and thus , by extension reducing nutrient
uptake subsequently and plant growth (Fageria and Moreira, 2011). Proximity of seed to
fertiliser is important in assessing the risk of germination damage.
REFERENCES
Bloom AJ. 1997. Nitrogen as a limiting factor: crop acquisition of ammonium and nitrate. In: Jackson LE, ed. Ecology in Agriculture. San Diego: Academic Press, 145–172.
Breazeale, J.F., 1906. Effect of certain solids upon the growth of seedlings in water cultures. Botanical Gazette 41, 54e63. Chan KY, Van Zwieten L, Meszaros I, Downie A, Joseph S (2007). Agronomic values of greenwaste biochar as a soil amendment. Australian Journal of Soil Research 45, 629–634. doi:10.1071/SR07109. Downie, A., A. Crosky and P. Munroe. 2009. Physical properties of biochar. In ‘Biochar for environmental management : Science and technology.’ (Eds J Lehmann and S Joseph) pp. 13-32. Earthscan: London ; Sterling, VA, USA. Craigie, R.A., 2011. Biochar incorporation into pasture soil suppresses in situ nitrous oxide emissions from ruminant urine patches. Journal of Environmental Quality 40, 468e476.
Epstein E, Bloom AJ. 2005. Mineral Nutrition of Plants: Principles and Perspectives, 2nd edn. Sunderland, MA: Sinauer Associates.
Fageria N K and Moreira A 2011 The role of mineral nutrition on root growth of crop plants. Advances in agronomy 110, 252-318.
Haefele, S.M., Knoblauch, C., Gummert, M., Konboon, Y., Koyama, S., 2009. Black carbon (biochar) in rice-based systems: characteristics and opportunities. In: Woods, W.I., Teixeira, W.G., Lehmann, J., Steiner, C., WinklerPrins, A.M.G.A., Rebellato, L. (Eds.), Amazonian Dark Earths: Wim Sombroek’s Vision. Springer, Berlin, pp. 445e463. Hass, A., J.M. Gonzalez, I.M. Lima, H.W. Godwin, J.J. Halvorson, and D.G. Boyer. 2012. Chicken manure biochar as liming and nutrient source for acid Appalachian soil. J. Environ. Qual. 41:1096–1106 (this issue). doi:10.2134/jeq2011.0124.
Irwin, M.P.S., 1981. The birds of Zimbabwe, Quest Pub.
Kammann, C., S. Ratering, C. Eckhard, and C. Muller. 2012. Biochar and hydrochar eff ects on greenhouse gas (carbon dioxide, nitrous oxide, methane) fl uxes from soils. J. Environ. Qual. 41:1052–1066 (this issue). doi:10.2134/jeq2011.0132. Laird, D.A., Chappell, M.A., Martens, D.A., Wershaw, R.L. and Thompson, M., 2008. Distinguishing black carbon from biogenic humic substances in soil clay fractions. Geoderma 143(1-2): 115-122. Lehmann J, de Silva JP Jr, Steiner C, Nehls T, Zech W, Glaser B (2003) Nutrient availability and leaching in an archaeological Anthrosol and a Ferralsol of the Central Amazon Basin: fertilizer, manure and charcoal amendments. Plant and Soil 249, 343-357.
Novak, J.M. et al., 2009. Impact of biochar amendment on fertility of a southeastern Coastal Plain soil. Soil Science, 174(2), p.105.
Makoto, K., Tamai, Y., Kim, Y.S., Koike, T., 2010. Buried charcoal layer and ectomycorrhizae cooperatively promote the growth of Larix gmelinii seedlings. Plant and Soil 327, 143e152.
Major, J. (2010). Biochar for soil fertility enhancement and climate change mitigation. Montreal, Quebec.
Matsubara, Y.I., Harada, T., and Yakuwa, T., Effect of inoculation density of VAM fungal spores and addition of carbonized material to bed soil on growth of Welsh onion seedlings, J. Jpn. Soc. Hortic. Sci., 64, 549–554 (1995). Nyamapfene, K.W., 1991. The soils of Zimbabwe, Nehanda Publishers.
Shinogi Y., Yoshida H., Koizumi T., Yamaoka M., and Saito T., 2003. Basic characteristics of lowtemperature carbon products from waste sludge. Advances in Environmental Research 7: 661-665. Steiner, C.,Teixeira,W.G., Lehmann, J., Nehls,T., Macedo, J. L.V., Blum,W. E. H. and Zech,W.2007). ‘Long term effects of manure, charcoal and mineral fertilization on crop production and fertility on a highly weathered Central Amazonian upland soil’, Plant and Soil, vol 291, pp275–290 Taghizadeh-Toosi, A., Clough, T.J., Condron, L.M., Sherlock, R.R., Anderson, C.R., Tyron E.H., 1948. Effect of charcoal on certain physical, chemical and biological properties of forestsoils. Ecological. Monographs. 18: 82–115. Topoliantz, S., Ponge, J.F., 2005. Charcoal consumption and casting activity by Pontoscolex corethurus (Glossoscolecidae). Applied Soil Ecology 28, 217e224. Van Zwieten, L, Kimber, S, Downie, A, Morris, S, Petty, S, Rust, J & Chan, KY 2010a, ‘A glasshouse study on the interaction of low mineral ash biochar with nitrogen in a sandy soil’, Australian Journal of Soil Research 48(6–7): 569–76. Van Zwieten, L, Kimber, S, Morris, S, Chan, KY, Downie, A, Rust, J, Joseph, S & Cowie, A 2010b. ‘Effects of biochar from slow pyrolysis of papermill waste on agronomic performance and soilfertility’, Plant and Soil 327(1–2): 235–46. Vookova, B., Kormutak, A., 2001. Effect of sucrose concentration, charcoal, and indole-3-butyric acid on germination of Abies numidica somatic embryos. Biologia Plantarium 44, 181e184.
Walter A, Feil R, Schurr U. 2003. Expansion dynamics, metabolite composition and substance transfer of the primary root growth zone of Zea mays L. grown in different external nutrient availabilities. Plant, Cell and Environment 26: 1451–1466.
Yamato, M., Okimori, Y., Wibowo, I.F., Anshori, S. and Ogawa, M., 2006. Effects of the application of charred bark of Acacia mangium on the yield of maize, cowpea and peanut, and soil chemical properties in South Sumatra, Indonesia. Soil Science and Plant Nutrition, 52(4): 489-495.
CHAPTER 4 THE EFFECTS OF SEWAGE SLUDGE BIOCHAR ON ABSOLUTE GROWTH RATE, RELATIVE GROWTH RATE AND PLANT HEIGHT OF MAIZE IN RED FERSIALLITIC 5E SOILS IN ZIMBABWE.
4.1. INTRODUCTION
The term plant growth analysis refers to a useful set of quantitative methods that describe and
interpret the performance of whole plant system grown under natural, semi natural, or
controlled conditions . Plant growth analysis provides an explanatory, holistic, and integrative
approach to interpreting plant form and function. It uses primary data such as weights, areas,
volumes to investigate processes within and involving the whole plant or crops.
Organic manure such as crop residues, green manure, compost, farm yard manure, animal
wastes, municipal wastes, oil cake, and residues from food processing, can be used as an
alternative or supplement for inorganic fertiliser. Nutrients contained in organic manures are
released more slowly and are stored for longer time in the soil, thereby ensuring a long
residual effect (Sharma and Mittra, 1991), supporting better root development and higher
crop yield (Abou El-Magd, Mohammed and Fawzy, 2005), activates soil microbial biomass
thereby increasing soil fertility.
Several studies have shown that biochar amendment can enhance the growth and quality of
certain crop plants, although the mechanisms by which it does so are far from clear. As
observed by Jones (1976), yield of maize is significantly related to plant size: dry matter yield
in the early stages of maize growth would enhance grain yield. One of such cultural practices
is soil amendment by application of organic manure.
Sewage sludge biochar will help in the long-term improvement of soil fertility. During plant
vegetative growth, the flow of nitrogen from older to younger organs occurs at different
speeds, and the main source of nitrogen is always soil (Grezebisz, 2008). In the maturation
period, nitrogen taken up from the soil accounts for only a small portion of nitrogen
accumulated in generative organs (grains).
Most nitrogen comes from remobilisation of this element that was previously accumulated in
vegetative organs. Therefore, the more nitrogen is accumulated in the plant vegetative
organs/leaves the greater should be the yield. Numerous and regular applications of biochar
to soil are not necessary because biochar is not warranted as a fertiliser (Lehmann and
Joseph, 2009). In a pot trial carried out by Chan et al. (2007), a significant increase in dry
matter (DM) production of radish when N fertiliser was used together with biochar. The
results showed that in the presence of N fertiliser, there was a 95% to 266% variation in yield
for soils with no biochar additions, in comparison to those with the highest rate of 100t/ha.
Improved fertiliser-use efficiency, referring to crops giving rise to higher yield per unit of
fertiliser applied (Chan and Xu, 2009), was thus shown as a major positive attribute of the
application of biochar.
Major, (2010) conducted a study whereby a field trial demonstrated that a single dolomitic
lime and wood biochar application on an acidic, infertile Oxisol was sufficient to increase
crop yield and nutrition uptake of crops. A maize-soybean rotation was used for the study
which took place over several cropping seasons. In addition, inorganic fertilisers were equally
applied to both the biochar-amended and control soils. The maize yield gradually increased
with an increase in the biochar application rate in the ensuing years for the four years. These
yield increases were as a result of increases in pH and nutrient retention.
Furthermore, Lehmann et al. (2003) attributed the increase plant growth responses observed
to greater plant uptake of K, P, Ca, Zn and Cu with increasing biochar applications. In a study
conducted by Vaccari et al. (2011) positive effects on the growth, yield and grain quality of
durum wheat were observed when a large scale application of biochar was made. In general,
coarse-textured soils have a high risk of nutrient leaching that limits plant nutrient uptake,
fertiliser use efficiency and yield.
Growth analysis can be used to provide insight into any crop response to a fertiliser
application design and to the climate and its ultimate effect on yield. The objective of this
study was to determine the effect of biochar and fertiliser application rate on the relative
growth rate, absolute growth rate and plant height of maize grown in red loam soils. It also
looks at the response of maize to fertiliser use efficiency following biochar application.
4.2. MATERIALS AND METHODS
4.2.1. Site description
The experiment will be conducted in the field at Africa University (AU) farm. The soil at AU
is a red Fersiallitic 5E soil under Zimbabwe soil classification system. The soils are strongly
sandy clay loamy soils (Nyamapfene, 1991). The average annual temperature is 19 °C,
surprisingly low for its moderate altitude (about the same as Harare which is 360 metres
higher.) This is due to its sheltered position against the mountain ridge of Cecil Kop which
encourages cool breezes from lower altitude to the east and south. The coldest month is July
(minimum 6 °C and maximum 20 °C) and the hottest month is January (minimum 16 °C and
maximum 26 °C), although as in much of Zimbabwe, October has the hottest days (28 °C).
The annual rainfall is 818 mm. Rain falls mostly in the months December to February
although heavy showers are possible before and after this period. The wettest month on
record was January 1926 which received 580 mm while January 1991 received only 24 mm
(Irwin, 1981).
4.2.2. Description of the crop variety to be used.
CROP VARIETY General Comments MAIZE SC403 SC 403 is a very early white Maize Streak and Mottle
Viruses tolerant hybrid, with a relatively short, flinty ear and excellent yield stability over a range of environments with relatively slow dry down rate. It has outstanding drought tolerance with very good synchronization of silks. In numerous trials in communal areas over several seasons, SC 403 has performed very well under drought conditions. On average, SC 403 has a higher yield potential over SC 401. SC 403 has hard, very dense grain and has outstanding tolerance to both Diplodia and Furasium cob rots. SC 403 is widely recommended for harsh conditions where yields of less than 6t/ha are expected. It is also recommended for irrigation schemes an early Maize Streak Virus tolerant hybrid is required.
4.2.3. Experimental design: BIOCHAR IN MAIZE The experiment will be a Randomized Complete Blocks Design (4 blocks) with five
treatments. The treatments will be:
1. 15 tons/ha biochar + 150Kg/ha AN (34.5%) top dressing
2. 15 tons/ha biochar and 300 kg/ha Compound D (7:14:7, N: P2O5:K2O) fertilizer +
150Kg/ha AN (34.5%) top dressing
3. 15 tons/ha biochar and 150kg/ha Compound D fertilizer+ 150Kg/ha AN (34.5%) top
dressing
4. 300kg/ha compound D fertilizer + 150Kg/ha AN (34.5%) top dressing
5. No amendment (control)
4.3Agronomic practices 4.3.1Planting
Maize will be planted in 90 cm inter-rows with intra-row spacing of 60 cm giving a plant
population of 37 000 plants. The plot will be 4*4 square meters in size. The seeds will be
buried manually into the soil for 4 cm and two seeds placed at each planting station.
4.3.2 Biochar and Fertilizer application
Biochar will be evenly spread on the soil surface. One and half kilograms (1.5 Kg/m2) of
biochar per every square meter will be applied. It will then be incorporated into the soil
before planting by hand hoeing. Biochar will be obtained from the pyrolysis of sewage sludge
from Mutare city council waste and water treatment department. Care should be taken as a lot
of dust is produced when applying. Fertilizers will be applied per plant station using fertiliser
cups as per the soil requirements and recommendations. Compound D will be applied as a
basal dressing at planting while AN (34.5%) will be applied as a top dressing at 4-6 weeks
after planting.
4.3.3 Weeding
Weeds will be controlled by hand-hoeing.
4.3.4. Watering
Maize plants will be watered with 2.5cm of water per week as supplementary irrigation in
absence of rainfall to reach their maximum potential. It will be of importance to put into
account the amount rain that falls in the area when determining how much to water.
4.4. DATA COLLECTION
4.4.1 Biomass
The above ground biomass will be determined at six weeks, ten weeks after planting and at
harvesting by cutting the whole crop just above the soil surface and oven dried for 72 hours at
600C. The dry weight will then be determined by weighing the dry crop parts. These values
will be used in calculating absolute and relative growth rates.
4.4.2. Absolute Growth Rate (AGR)
Increase in total dry weight per plant per unit time.
� [Note: - this growth index is used specifically to quantify growth of single plants (e.g.:
in pot experiments) where the components of a crop (i.e. a plant population) spread
over a given land area is absent.]
AGR=
Where, W1 and W2 are total dry weight per plant at times t1 and t2 respectively.
4.4.3. Relative Growth Rate (RGR)
Increase of total dry weight per unit time per unit of existing total dry weight.
RGR= X
Where, W is the mean total dry weight during the period (t2-t1).During the linear phase of the
growth curve W can be calculated as the simple arithmetic mean of W1 and W2.
4.4.4. Plant height
The plant heights will be measured on a weekly basis using measuring meter stick. Plants will
be sampled randomly and ten plants will be sampled each time. This will be computed to
determine plant early growth rate. This will be done from week six to week ten after crop
emergence.
4.5. DATA ANALYSIS
The effect of biochar or biochar and compound D mixture on the relative growth rate,
absolute growth rate and plant height were analysed using GenStat Release 7.2 DE.Where
significant effects were detected in the ANOVA (P=0.05), means were compared using least
significant difference. For data where no significant effects were observed, means and
standard errors are presented.
4.6. RESULTS
)12(
)12(
tt
WW
−−
W
1)12(
)12(
tt
WW
−−
There were significant difference on absolute growth rate and relative growth rate among
treatments (P<0.05).
Table 1: Shows the absolute and relative growth rate means for the five treatments
Figure 1 below shows the plant heights taken from week four to eight. The relative growth
rates were calculated from these plant heights to give the weekly growth rates. It can be seen
that the growth rates increased from the first week of recording to the eighth week showing
progressive growth in maize.
Figure 1: Plant heights and relative growth rates from week four to eight. An increase in the
biomass did not translate to increased relative growth rate but had a positive correlation with
absolute growth rate.
0
20
40
60
80
100
120
140
160
180
200
trtnt 1 trtnt 2 trtnt 3 trtnt 4 trtnt 5
plant height 1
plant height 2
plant height 3
plant height 4
rgr 1
rgr 2
rgr 3
Figure 2: Shows the relative and absolute growth rates calculated from the biomass taken at
week four and week eight after emergence (biomass 1 and 2 respectively)
Figure 3: shows the shows relationship between plant height and biomass taken at week four
and eight after crop emergence
0
1
2
3
4
5
6
trtnt 1 trtnt 2 trtnt 3 trtnt 4 trtnt 5
Biomass 1
Biomass 2
Absolute growth rate
Relative growth rate
0
20
40
60
80
100
120
140
160
180
200
trtnt 1 trtnt 2 trtnt 3 trtnt 4 trtnt 5
biomass 1
biomass 2
plant height 1
plant height 4
4.7. Discussion
Full fertiliser application with biochar showed the highest absolute growth rate and relative
growth rate. Reducing the fertiliser application to half the recommendation and applying it
with biochar showed no significant difference (P<0.05) with full fertiliser application rate.
Biochar alone showed no significant difference with the control (P<0.05) confirming earlier
studies that biochar is not a fertiliser. Biochar has the greatest ability to enhance plant growth
and nutrient content when combined with fertiliser application (Blackwell et al., 2009).
Neutral and negative plant growth responses have been observed with biochar-only
amendments, yet when combined with fertiliser additions, crop yields are increased to much
greater extent than with fertiliser additions in absence of biochar (Asai et al., 2009; Blackwell
et al., 2009). Decreased growth is regularly reported with biochar amendments when not
associated with fertiliser additions (Asai et al., 2009; Gaskin et al., 2010).
Numerous and regular applications of biochar to the soil are not essential because biochar is
not a fertiliser (Lehmann and Joseph, 2009). In a pot trail carried out by Chan et al., (2007), a
significant increase in the dry matter production of radish resulted when N fertiliser was used
together with biochar. The results showed that in the presence of N fertiliser, there was a 95
to 266% variation in yield for soils with no biochar additions, in comparison to those with the
highest rate of 100 t /ha. Improved fertiliser-use efficiency, referring to crops giving rise to
higher yield per unit fertiliser applied (Chan and Xu, 2009), was thus shown as a major
positive attribute of the application of biochar.
As the plant height increased from four to eight weeks after emergence, the relative growth
rates also increased as shown in figure 1. Figure 2 showed that an increase in the biomass
only affected the absolute growth rate but did not translate to an increase in the relative
growth rate. A huge increase in the plant height gave very small changes in the biomass of
the crop. Full fertiliser application with biochar showed increased plant heights. Since
biochar reduces exchangeable acidity, increased soil pH of acidic soils, and inherently
contains significant amounts of plant nutrients such as potassium, calcium and magnesium, it
is suggested that these are the main reasons for enhanced plant growth (Chan and Xu, 2009)
Increases in biomass will mean an increase in the photosynthetic capacity. This helps in
increasing the source of assimilate for the reproductive structures which might translate to an
increased grain yield. According to Grzebiesz (2008), most carbon accumulated in grain
comes from running photosynthesis of photosynthetically active organs. The grain demand
for assimilates is so high that generative and vegetative organs or particular generative
structures compete with each other. The older the acceptor, the greater the odds on its
accumulation of a respectively high amount of carbon, which obviously has its repercussions
for the amount of produced generative yield.
References
Abou El-Magd, M. M., Hoda Mohammed, A. and Fawzy, Z. F. (2005) . Relationships, growth and yield of broccoli with increasing N, P or K ratio in a mixture of NPK fertilizers. Annl. Agric. Sci. Moshtohor., 43 (2): 791-803. Asai, H., B.K. Samson, H.M. Stephan, K. Songyikhangsuthor, K.Homma, Y. Kiyono, Y. Inoue, T. Shiraiwa and T. Horie. 2009. Biochar amendment techniques for upland rice production in Northern Laos: 1. Soil physical properties, leaf SPAD and grain yield. FieldCrops Research. 111:81-84. Blackwell P, Reithmuller G, Collins M, 2009. Biochar application to soil. In Biochar for Environmental Management. (Eds J Lehmann and S Joseph) pp. 207-226. (Earthscan: London). Chan K and Xu Z, 2009. Biochar: Nutrient Properties and Their Enhancement. In ‘Biochar forEnvironmental Management: Science and Technology’. (Eds J Lehmann and S Joseph) pp.53-66. (Earthscan: London, UK). Chan K. Y, Van Zwieten L, Meszaros I, Downie A, Joseph S (2007), Agronomic values of greenwaste biochar as a soil amendment. Australian Journal of Soil Research 45, 629–634. doi:10.1071/SR07109. Gaskin J.W., R.A. Speir, K. Harris, K.C. Das, R.D. Lee, L.A. Morris and D.S. Fisher. 2010. Effect of Peanut Hull and Pine Chip Biochar on Soil Nutrients, Corn Nutrient Status, and Yield. Agronomy Journal. 102:623-633.
Grzebisz W, 2008. Fertilisation of crops. Pt. I. the basics of fertilisation. Polish. Jones M. J, 1976. Planting time studies on maize at Samarau, Nigeria. Samaru Miscellaneous paper 58. Institute for Agric. Res. Samaru. pp. 1-21. Lehmann C. J, and Joseph. S, 2009. Biochar systems. In ‘‘Biochar for Environmental Management: Science and Technology’’ (C. J. Lehmann and S. Joseph, Eds.), Earthscan, London. Lehmann. J, de Silva. J. P Jr, Steiner. C, Nehls. T, Zech. W, Glaser. B , 2003. Nutrient availability and leaching in an archaeological Anthrosol and a Ferralsol of the Central Amazon Basin: fertilizer, manure and charcoal amendments. Plant and Soil 249, 343-357. Major. J, 2010. Biochar for soil fertility enhancement and climate change mitigation. Montreal, Quebec. Sharma, A. R. and Mittra, B. N, 1991. Effect of different rates of application of organic and nitrogen fertilizers in rice-based cropping system. J. Agr. Sci. (Camb.) ,117: 313-318. Vaccari .F. P, Baronti. S, Lugata. E, Genesio. L, Castaldi. S, Fornasier. F and Miglietta. F, 2011. Biochar as a strategy to sequester carbon and increase yield in durum wheat. European Journal of Agronomy 34, 231-238.