Andrew Rees started to question the grassland management at Moor Farm, Haverfordwest, where he farms with his wife, Vicky, and mother, Jean, three years ago. Since then, he has cut nitrogen use by more than 60% and planted herbal leys or cover crops across a fifth of the farm.

To help understand cover crop decomposition and N release throughout the growing season, University of Nebraska researchers designed a study using “litterbags” — a common method to research crop decomposition. This research is part of the Precision Sustainable Agriculture (PSA), a collaborative project supported by the Agriculture and Food Research Initiative’s Sustainable Agricultural System Coordinated Agricultural Projects from the United States Department of Agriculture (USDA).

Nitrate leaching is a major concern in coarse-textured agricultural soils because it can cause economic losses for farmers and contaminate groundwater. While some nitrate leaching may be inevitable when growing corn on sandy soils, there are several management strategies that can be implemented to limit nitrate loss. Here are some key takeaways from a recent five-year study looking at three major factors impacting nitrate leaching: drainage, nitrogen availability, and cropping system.

Legumes still can provide valuable N to today’s cropping systems. Legumes also contribute a non-nitrogen rotation effect due to addition of soil organic matter and improvement in soil health. Corn grown following alfalfa stands that are 2+ years old (and contained at least 50% alfalfa) require no nitrogen fertilizer on many soils. Red clover N credits are less than for alfalfa.

Cover crops were almost as effective as restored prairie at reducing nitrate concentrations in tile-drained water, according to recent research at Iowa State University.This was one of the key findings from a study led by Marshall McDaniel, associate professor of agronomy at Iowa State. The project was designed to better understand how the quantity and quality of tile drainage water impacts in-stream potential for nutrient enrichment, leading to growth of algae and depletion of vital oxygen in aquatic ecosystems.

Cover crops are used to address multiple resource concerns and can provide a wide range of conservation benefits including reduced soil erosion, scavenged residual soil nitrogen, weed suppression, and supplemental livestock forage. The carbon to nitrogen (C:N) ratio of the cover crop determines the durability of the cover crop residue.