Profitability of No‐Tillage Corn following a Hairy Vetch Cover Crop

Hairy vetch (Vicia villosa Roth subsp. villosa), as a winter legume cover crop, fixes atmospheric N2 for following crops and improves the soil. A 3‐yr field study (1985‐1988) was conducted in the Maryland Coastal Plain and Piedmont to assess the agronomic and economic characteristics of a hairy vetch cover crop on no‐till corn (Zea mays L.) compared with corn systems preceded by winter fallow and winter wheat (Triticum aestivum L.) cover crops. No‐till corn following a hairy vetch cover crop yielded more than no‐till corn following winter fallow and winter wheat cover crops at comparable fertilizer N rates in the Coastal Plain and Piedmont over 3 yr. The highest yielding combinations were a hairy vetch cover crop with 120 lb N/acre in the Coastal Plain and a hairy vetch cover crop with 40 lb N/acre in the Piedmont. The most profitable combinations were a hairy vetch crop with 120 lb N/acre in the Coastal Plain and a winter fallow with 40 lb N/acre in the Piedmont. for risk averse farmers, a hairy vetch cover system was the most desirable choice at both locations. Using profit maximizing criteria to select optimum N rates, hairy vetch is more accurately a yield of enhancer for no‐till corn than a N substitute. Breakeven costs for hairy vetch seed and fertilizer N were estimated by comparing the “best” hairy vetch system with the “best” winter wheat system under different scenarios at both locations. No‐till corn following a hairy vetch cover maintained its economic advantage over no‐till corn following winter wheat even when the price of hairy vetch seed was increased, the price of fertilizer N was decreased, and the average net returns of the hairy vetch system reduced by $10/acre to reflect a future herbicide application to kill volunteer hairy vetch. Research Question Many farmers are growing cover crops between periods of regular crop production to reduce soil erosion, add organic matter, improve soil physical condition, increase crop yields, and improve water use efficiency in no‐tillage systems for corn. In addition, legume cover crops such as hairy vetch fix atmospheric N for use by the subsequent corn crop. The primary objectives of this study were to evaluate the yield, profitability, and risk of no‐till corn following a hairy vetch cover crop as compared with winter wheat and winter fallow nonlegume cover crops. This 3‐yr study was conducted at two different locations in Maryland. Literature Summary In Kentucky, Maryland, Georgia, and the Appalachian region, hairy vetch was found to substantially reduce the following corn crop's requirements for fertilizer N. In terms of profitability, increased yields of corn more than compensated for the additional expense in seeding hairy vetch in Kentucky and Georgia. In other locations, the hairy vetch cover crop and no‐till corn system was approximately equal in net returns per acre to its alternatives. In Georgia, the hairy vetch cover system was also best for those farmers who are risk averse. Study Description A 3‐yr field study (1985–1988) was conducted in the Coastal Plain (Poplar Hill, MD) and Piedmont (Ellicott City, MD) to examine the N contributions by hairy vetch. Winter wheat and winter fallow were used as non‐legume checks. The experimental plot area was a different field each year at each location on which corn was the last crop. The rates of fertilizer N for specific covers at each location were 0 lb N/acre, one level between zero and the university recommended rate, the university recommended rate, and one level above the university reocmmended rate. No‐till corn was planted 5 to 15 d after covers were killed with a knockdown herbicide. The interval between herbicide application and corn planting was determined by cover crop growth, soil characteristics, and rainfall pattern. Corn yields were measured at 15.5% moisture. Profit for the various treatments was found by multiplying the corn yield by the price of corn and subtracting the appropriate costs of production. Risk was examined using a “safety first” criterion. This method assumes that a profit maximizing farmer seeks the highest level of profits subject to meeting a goal of a minimum level of profits. Applied Questions Which combinations of fertilizer N and cover crops gave the highest no till corn yield? In the Coastal Plain, a hairy vetch cover with 120 lb N/acre gave the highest corn yield, with 147 bu/acre. In the Piedmont, a hairy vetch cover with 40 lb N/acre gave the highest corn yield, with 122 bu/acre. The yield advantages of corn following hairy vetch in the Piedmont were not as great as in the Coastal Plain. Which combinations of fertilizer N and cover crops were most attractive economically for no‐till corn production? In the Coastal Plain, no‐till corn following a hairy vetch cover with 120 lb N/acre gave the highest average net return ($96/acre) when corn was priced at $2.40/bu (Fig. ). In the Piedmont, the most profitable combination was corn following winter fallow with 40 lb N/acre ($68/acre). The yield advantages of corn following hairy vetch in the Piedmont were not great enough to compensate for its extra expense. For risk averse farmers, which combinations of fertilizer N and cover crops were most profitable for no‐till corn production? Using a “safety first” criterion, a risk averse farmer will choose corn following hairy vetch in either the Coastal Plain or Piedmont (Fig. ). In the Coastal Plain, net returns for the hairy vetch system will exceed $57/acre in 3 of 4 yr. In the Piedmont, net returns for the hairy vetch system will exceed $30/acre in 3 of 4 yr. Recommendation For risk neutral farmers, we recommend the use of a hairy vetch cover crop with 120 lb N/acre for the production of no‐till corn in the Mid‐Atlantic Coastal Plain; in the Mid‐Atlantic Piedmont, we recommend the use of a winter fallow cover crop with 40 lb N/acre. For risk averse farmers, the same hairy vetch and fertilizer N rate is recommended in the Coastal Plain. A hairy vetch cover crop with 40 lb N/acre is recommended in the Piedmont, however. Highest average net returns of no‐till corn following three cover crops in Maryland Coastal Plain and Piedmont, 1986–1988 (corn price — $2.40/bu). Coastal Plain winter fallow and winter wheat received 0, 120, 180, and 240 lb N/acre and hairy vetch received 0, 40, 120, and 180 lb N/acre. All Piedmont cover crops‐received 0, 40, 100, and 180 lb N/acre. image Highest average lower limit of net returns of no‐till corn following three cover crops in Maryland Coastal Plain and Piedmont, 1986‐1988 (com price = $2.40/bu and 75% confidence level for lower limit). Coastal Plain winter fallow and winter wheat received 0,120, 180, and 240 lb N/acre and hairy vetch received 0, 40,120, and 180 lb N/acre. All Piedmont cover crops received 0, 40, 100, and 180 lb N/acre.