aging Cover Crops as a Nutrient Management Gruver Western Illinois University School of Agricu
Managing Cover Crops as a Nutrient Management Tool
Joel Gruver Western Illinois University School of Agriculture
This is impressive - we are doing more with less!!!
Unfortunately the story isn’t all positive
Illinois watersheds are delivering 20% of the N and 11% of the P but only 7% of the water
Annual grain production
systems are leaky, especially in high
precipitation environments.
The 4Rs can help but
conservation practices (in-
field and edge-of-field) are also needed.
Capture
Capture = CC uptake + immobilization by microbes eating high C residues
C
http://notillveggies.org/cover-crops-as-management-tools/
Click on boxes for related research by Weil et al.
In 2016 the OFN collected 2,172 samples
from 272 tile outlets across Iowa. Fields w/ CC
had 29% lower nitrate concentrations than
fields w/o cover crops and 40% lower total
nitrate loss (lbs/ac/yr).
In 2015, fields w/ CC had 23% lower nitrate
concentrations. field w/cover crops
CCs = cleaner water
fields w/o cover crops
Nitrate Leaching in Cover Crops and Corn/Soybean Systems in Southern Illinois
Rachel Cook, Assistant Professor of Soil Fertility, SIU-CarbondaleJon Schoonover, Professor of Physical Hydrology, SIU-Carbondale
Karl Williard, Professor of Watershed Management, SIU-Carbondale
Background and ObjectivesNitrogen loss to the environment remains one of the biggest issues facing agriculture today. Impacts on water quality can be significant and require immediate attention to develop best management practices to reduce nitrate leaching and run-off from agricultural fields. One suggested means of reducing nitrogen losses is through the use of winter cover crops, but there is very little information on the effect of cover crops on nitrate leaching, particularly in non-tile drained fields. Additionally, there is little information on the interaction of tillage and cover crop type (legume or non-legume) on potential leaching.
- Nitrate-N leaching was reduced by cover crop treatments during the late fall and winter, as the no cover crop plots consistently exhibited the highest nitrate-N levels - The highest DRP levels were observed immediately following DAP application and did not appear to be influenced by cover crop or tillage treatments - Shallow soil water nitrate-N levels were highest in the no cover till treatment in the dormant season, suggesting nitrate-N uptake by cover crops - In the paired watershed study, cover crops reduced soil water nitrate-N levels in all topographic positions following their establishment
Summary of key findings
CC and tillage system effects on concentration and depth of nitrate-N
When commodity prices are low,
IA Soybean Association’s On-Farm Network® Replicated Strip Trial Database
The negative CC effects on corn are likely related to nutrient immobilization and/or root
pathogens
Soybean health experiment – multiple locations across IL
MustardRapeseed
CanolaCereal ryeCereal rye
November 2010
Soybeans no-till drilled into cereal rye were the top yielder in 2011
incorporatedpre-plant
no-till
Publication in press
Abstract:
Field trials were conducted from 2010 to 2013 at four locations in Illinois to evaluate the impact of cover crops (cereal rye (Secale cereale), brown mustard (Brassica juncea), winter canola (Brassica napus), and winter rapeseed (B. napus) on soybean (Glycine max) stands and yield, diseases, pathogen populations, and soil microbial communities. Cover crops were established in the fall each year, and terminated the following spring either by using an herbicide (no-till farms), by incorporation (organic farm), or by an herbicide followed by incorporation (research farm). Although shifts in soilborne pathogen populations, microbial community structure were not detected, cover crops were found to induce general soil suppressiveness in some circumstances. Cereal rye and rapeseed improved soybean stands in plots inoculated with Rhizoctonia solani and decreased levels of soybean cyst nematode in the soil. Cereal rye increased soil suppressiveness to R. solani and Fusarium virguliforme, as measured in greenhouse bioassays. Cereal rye significantly improved yield when Rhizoctonia root rot was a problem. Using cover crops repeatedly, in the same field, may achieve more distinct effects on suppressing soybean diseases and build-up beneficial properties in the soil.
Healthier roots → > nutrient uptake
Early planting trade-offs – Risk vs. Rooting depth
Plant and Soil August 2001, Volume 235, Issue 2, pp 127-133
Establishment of Bradyrhizobium japonicum for soybean by inoculation of a preceding wheat crop R. J. Goos, B. E. Johnson, P. M. Carr
Abstract
On fields with no history of soybean (Glycine max (L.) Merr.) production, inoculation alone is often inadequate to provide for adequate nodulation the first time this crop is grown. The objective of this study was to determine if inoculation of spring wheat (Triticum aestivum L.) seed with Bradyrhizobium japonicum would lead to an increase of B. japonicum numbers in the soil, and improve nodulation of a subsequent soybean crop. In the greenhouse, wheat seed inoculation increased B. japonicum numbers from undetectable numbers to greater than 9000/g soil, whereas the numbers of introduced B. japonicum declined in unseeded pots. In the field, inoculation of wheat seed increased B. japonicum numbers in the soil from undetectable levels to greater than 4000/g soil the following year. When soybean seed was inoculated, but grown in soil devoid of B. japonicum, nodules formed only near the point of seed placement. The heaviest nodulation, and widest distribution of nodules in the topsoil were found when B. japonicum was established the year before by wheat seed inoculation, plus soybean seed inoculation. Wheat seed inoculation the year before growing soybean, combined with proper soybean seed inoculation, should provide for abundant nodulation the first time soybean is grown on a field.
+20 lbs N/a
A little extra N can make a big difference
2x biomass
Effect of kill date on typical plant available N (PAN) release from cereal, legume, or mixed stands. Based on compilation of field data from Willamette Valley cover crop trials. Source: D. Sullivan
Cover crop treatment
0
30
60
90
120
150
Soi
l te s
t P, m
g/kg
a a
c
bbc
Wye, Fall 2003Means for 0-45 cm
Third year of cover crop treatments in a corn-soybean rotation
Brassicas appear to be particularly
adept at solubilizing P
Soil Test PSilt loam at Wye, fall 2003Means for top 18 inches
Biological pumping + organic acid root exudates
50% increase
Nutrient cycling: Phosphorus
may be large enough to justify extending your rotation
Frost seeded red clover is a more reliable producer of biomass and fixer of N than legume CCs planted after small
grain harvest
Frost seeded red clover is
more weather resilient
More than most
legumes
Wisconsin data suggest that approximately 70% of whole-plant N will become available in the first year following clover, most released before corn begins its
period of rapid uptake.
Good timing!!
Wisconsin data suggest that approximately 70% of whole-plant N will become available in the first year following clover, most released before corn begins its
period of rapid uptake.
Good timing!!
Multispecies CC mixesare much more of an option after small grains
http://www.greencoverseed.com/
This is a very useful tool for planning CC mixes!
Excellent nutrient scavenger Excellent N fixer
Oilseed sunflower Sunn hemp
Must be planted by planted by ~8/15 in
the central Corn Belt
11/6/2016 at the WIU Organic Research Farm
Sizing residues, increasing soil contact and planting a very low rate of cereal rye (12 lbs/a)
Additional CC species will be spring planted to provide bee forage and mulch/green manure prior to planting CT and NT pumpkins
Likely species include balansa and berseem clover, phacelia, camelina, mustard…
Cereal rye rates ranging from 12 to 120 lbs/a were easily and quickly dialed in
?