Management of Tropical Sandy Soils for Sustainable Agriculture
Nitrogen Management on Sandy Soils: Review of...
Transcript of Nitrogen Management on Sandy Soils: Review of...
Nitrogen Management on Sandy Soils: Review of BMPs
Carl Rosen Department of Soil Water and Climate University of Minnesota
Central MN Irrigation Workshop Thumper Pond, Ottertail, MN February 25, 2014
Topics Covered
Background for development of BMPs Understanding the N cycle Risk for N losses and optimizing
yield
Examples of specific BMPs for sandy soils
Definition of Best Management Practices for Nitrogen
Economically sound, voluntary practices that are capable of minimizing contamination of surface and groundwater with nitrate-N
Based upon the concept of total N management Account for all sources of on-farm N Appropriate timing of application
Development is based on research conducted
primarily by the University of Minnesota - Replicated studies at experiment stations and on-farm
General BMPs
Account for all sources of N N used in starter fertilizer or other fertilizer sources Legume credit Manure credit
Test manure for nutrient content Calibrate spreader Do not spread on sloping frozen soil Inject or incorporate
Irrigation water
General BMPs Select an appropriate N rate Probably the most important BMP Probably the most difficult to determine How much N is supplied from soil? How much
additional N is needed? Uncontrollable factors
Temperature Rainfall
N rate is determined based on the crop grown and
other numerous factors
Appropriate N Rates for Corn Productivity characteristics of production
environment (soil and climate) Irrigated sandy soils – high productivity Non-irrigated sandy soils – medium productivity
Cost of N fertilizer/value of a bushel of corn
Producers attitude toward risk
Regional approach to N rates in the Corn Belt
Background for N Rate Recommendations Minnesota adopted N guidelines based on
the MRTN in 2006
Database for sandy soils was old and lacked sites that had enough N rates to establish a good response curve
We decided to use the high productivity N database for rain-fed heavy textured soils for N guideline
Background (continued)
Minnesota irrigated sandy soils are highly productive, but also at high risk of leaching
Reliable reports that new N guidelines were not
working on irrigated sandy soils
N rate recommendations for sandy soils are being revised and will be discussed in the next talk
Other N Management Considerations
N timing N source Method of application Use of inhibitors Urease and nitrification inhibitors Numerous products on the market N-Serve traditional nitrification inhibitor
Coated products (example – ESN)
Nitrogen Timing
Generalized N uptake for corn through the season
https://www.pioneer.com/home/site/us/agronomy/library/template.CONTENT/guid.1BF7B8F5-99E6-DC1E-0D45-9F5D240A8761
Nitrogen Timing – Sandy Soils
Recommended: Use split applications of N Incorporate/inject all N applications at least 3” or if
irrigated apply irrigation after application Use N inhibitor (N-Serve) for labeled crops when
early sidedress is used Follow proven water management practices to
prevent over-irrigation
Nitrogen Timing – Coarse-textured Acceptable – greater risk
Spring preplant application with N-Serve Single sidedress application early in the growing season
without an inhibitor Spring preplant with coated urea (ESN)
Not recommended
Fall application of any N source with or without N-Serve Spring preplant without N-Serve N fertilizer applied after tasseling Coated fertilizer to edible beans after planting
Nitrogen Timing – Coarse-textured
Study shows benefit of using N-Serve with preplant N But split application with N-Serve allowed a lower N rate With higher yields
Nitrogen Timing – Irrigated Potatoes on Coarse-textured soils
Increasing N in starter increased leaching potential and negatively affected yield
On-going BMP research
New technologies Stalk nitrate test
Post-mortum Report card
Sensors Chlorophyll meter Greenseeker Crop circle Remote sensing by plane
Inhibitors and coated urea products
Summary and Conclusions BMP development is based on
credible scientific studies – more studies on sand needed
Recommendations take into account the risk for N losses and optimization of yields
Nitrogen is leaky and getting it right every time is a challenge
Research is on-going and new technologies will help in improving N use efficiency and reducing N losses