Nitrogen-Fixing Winter Cover Crops and Production Risk: A Case Study for No-Tillage Corn

Abstract

Winter legumes can substitute for applied nitrogen fertilization of corn. Stochastic dominance was used to order net revenues from legume and applied nitrogen alternatives. Stochastic dominance orderings indicate that systems combining vetch with low applied nitrogen fertilization (50 and 100 pounds/acre, respectively) were risk inefficient. By contrast, vetch and 150 pounds/acre applied nitrogen maximized expected net revenue and was risk efficient for a wide range of risk-averse and risk-seeking behavior. Farmers with these risk attitudes may not reduce applied nitrogen if they switch to a vetch cover. Extremely risk-averse or risk-seeking farmers would not prefer winter legumes.

A review of economic considerations for cover crops as a conservation practice

“…Hairy vetch has been found to be consistently profitable in small-grain rotations (Lu et al, 2000; Snapp et al, 2005). Using experiment-station test plots, Larson et al (1998) found Tennessee no-till corn yields across five N rates [0–224 kg ha −1 (0–200 lbs ac −1 )] favored a hairy-vetch cover crop opposed to no cover crop at each application level. Average yield increases were as much as 2.82 Mg ha −1 (45 bu ac −1 ) at 0 kg of N and as small as 0.50 Mg ha −1 (9 bu ac −1 ) at 168 kg (150 lbs) (Larson et al, 1998).…”

“…Producers who do not reduce their N application rate in accordance with available legume-fixed N may be failing to gain the fertilizer benefit of raising the legume altogether (Larson et al, 1998; Johnson and Raun, 2003). However, multiple studies have shown that with a corn cash crop, even cover crops that fix large amounts of N cannot replace all applied fertilizer (Power et al, 1991; Lu et al, 2000; Snapp et al, 2005).…”

Demographic and Management Factors Affecting the Adoption and Perceived Yield Benefit of Winter Cover Crops in the Southeast

“…Use of legumes can provide additional N for the following cash crop, reducing the need for commercial fertilizer. However, farmers may not adjust N fertilization rates to the cash crop immediately following the cover crop due to potentially limited availability of N provided by the cover crop or risk-averse behavior (Dabney, Delgado, and Reeves, 2001;Larson et al, 1998;Lu et al, 2000). Thus, the net benefit of using a legume cover crop may be lower if N fertilization rates are not adjusted accordingly to take account of the N provided by the cover crop.…”

“…Incorporation of cover crop residues in the soil as a green manure with recommended applications of N fertilizer to the cash crop have been shown to increase crop yields (e.g., Bauer, Camberato, and Roach, 1993). Larson et al (1998) show that risk-averse farmers would be likely to adopt legume cover crops, but are not likely to reduce the amount of N applied to the cash crop. Farmers exhibiting this type of behavior did not likely experience an increase in the perceived yield from the use of a legume cover crop.…”

Agronomic Benefit and Economic Potential of Introducing Fall‐Seeded Pea and Lentil into Conventional Wheat‐Based Crop Rotations

“…They concluded that continuous spring wheat had a positive net return equivalent to winter wheat–fallow system, but all alternative spring crop rotations had a higher annual income variability than the traditional winter wheat–fallow system. Furthermore, Biermacher et al (2003), Larson et al (1998), and Stranger et al (2008) investigated the manner in which farmers’ risk attitudes affect their choice to alternative cropping systems and various N input levels. They found that these attitudes can alter decisions, and optimal choice is influenced by risk preferences and government programs.…”