Systematic design and evaluation of crop rotations enhancing soil conservation, soil fertility and farm income FACULTAD DE AGRONOMIA Dr. Santiago Dogliotti Attached Professor Plant Production Department FACULTY OF AGRONOMY – UNIVERSITY OF THE REPUBLIC URUGUAY
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Systematic design and evaluation of crop rotations enhancing soil conservation, soil fertility and farm income
FACULTAD DE AGRONOMIA
Dr. Santiago DogliottiAttached Professor Plant Production Department
FACULTY OF AGRONOMY – UNIVERSITY OF THE REPUBLICURUGUAY
Layout of the lecture
� Introduction
� Impact of crop rotation on crop yields and soil fertility
� Design criteria
� Design tools
� Prototyping
� ROTAT
� Farm Steps
� Evaluation criteria and evaluation tools
“A crop rotation is a sequence of crops grown in succession on a particular field”
Block 1b
Block 5b
Block 2b Block 3b Block 4b Block 6b Block 7b
Bl 2a Bl 2a
Bl 1a
Bl 4a
Bl 4a Bl 4a
Bl 3a Bl 5a
Bl 6a
Rotation effects on farm systems results
� Physical, chemical and biological soil fertility
� Crop yields
� Labor and inputs requirements = production costs
� Temporal distribution of the demand of labor and other resources, and cash flow
Rotation effect on potato yield (Scholte, 1989)
RotationPotato yield
(g/m2)
% of stems infested with V. daheliae
Potato monocropping
99 c 49 a
Maize - Potato 131 b 39 b
Sugar beet - Potato 118 bc 50 a
Maize - Sugar beet - Barley - Barley -
Potato152 a 21 c
Rotation effect on wheat yield (Berzsenyi et al., 2000)
• SOM (+)• Crop production (+)• Flooding (-)• Groundwater recharge (+)• Environm. impacts (-)
• Nutrient imbalance (-)• SOM (+)• Crop production (+)
Designing a crop rotation
Which are the main characteristics that define a crop rotation?� Crop species and families
� Frequency of each crop and crop family
� Sequences of crops
� Rotation length (time to complete a cycle)
Designing a crop rotation
1. Selection of crops• Profitability, market, constraints related to
farm resource availability
• Soil quality, water demand and climate requirements of crops
• Ensure variability in:� Botanical families
� Harvested organ
� Soil cover
� Residue/yield ratio
� Growth period
2. Crop sequences (Vereijken et al., 1997)� Never schedule successions of the same species
or the same family or crops sensitive to a soil borne disease relevant in the region.
� After a crop with a negative effect on soil fertility schedule a crop with positive effect: soil cover, rooting system, organic resiudes, harvested organ, N left.
� Take into account harvest and sowing periods of each crop including enough time for appropriate soil tillage.
Designing a crop rotation
3. Crop frequency
Estimated effect of crop frequency in the rotation on yield reduction from maximum yield (Molendijk y Mulder 1996).
Evaluation of a crop rotation in prototyping approach (After Vereijken et al., 1997)
Crop cover:No cover in autumn or winter = 0No cover in spring or summer = 1Partial cover in autumn or winter = 2Partial cover in spring or summer = 3Good cover = 4Very good cover = 5
Organic matter input:<1000 kg MS/año = 01000-2000 kg MS/año = 12000-3000 kg MS/año = 22000-3000 kg MS/año = 33000-4000 kg MS/año = 4>4000 kg MS/año = 5
Crop Soil coverCompactation due to tillage and harvest
Crop Growth Simulation models or experimental yields
Yield Reduction
Factors
♦ Cropping frequency (single crop, groups of crops)
♦ Inter-crop management and crop-crop successions
♦ Production techniques such as: irrigation, crop protection, mechanization
Production Activities filesClassified by soil type and management type with the yield of each crop in the rotation
DATABASE
Quantification Field level
RUSLE for crop rotationsROTEROSION
Long-term fate of soil organic matter
ROTSOM
N – P – K balance
EEP - calculator
Fodder calculator: energy, protein and qm
Labor distribution calculator: half month periods
Data handling program
SmartFarmerFarming systems
design program (MILP)
Farm Scale
Gross and Net margin, capital requirements at field level
Water balance at crop or crop rotation level
Software to aid design and evaluation ofrotations, explorative approach (Dogliotti, 2003)
Design and evaluation results
a
-500
0
500
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0 500 1000 1500
Labor (h ha-1)
Gro
ss
mar
gin
(U
S$
ha-1)
b
0
2
4
6
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1214
16
18
0 500 1000 1500Labor (h ha-1)
Soi
l ero
sion
(Mg
ha
-1)
c
0
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60
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100
120
140
0 500 1000 1500
Labor (h ha-1)
N s
urpl
us (k
g h
a-1
)
d
0
50
100
150
200
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450
0 500 1000 1500Labor (h ha-1)
EEP
soi
l (kg
-da
ys)
e
-400
-300
-200-100
0
100
200
300400
500
600
0 500 1000 1500
Labor (h ha-1)S
OM
rat
e (k
g ha
-1)
Gross margin, soil erosion, N surplus, EEP-soil and rate of change of SOM as a function of the labour requirement per ha of productionactivities designed for high mechanisation level (Dogliotti et al., 2004)
The Farm STEPS approach
1. The crop plan: Based on the current crop and animal activities of the farm and only few new activities, it optimizes family income subject to constraints related to resource availability and agronomic rules
2. The cropping plan: Based on the history and eligibility of each field, the crop plan and agronomic rules, it allocates crop sequences to fields to produce a land use plan for the next few years.
3. Ex-ante evaluation of the plan: Based on technical coefficients and semi-quantitative indicators it evaluates the economic and environmental results of the cropping plan