Development, Implementation and Evaluation of Low-input Crop and Livestock Systems for the Southern Region (88-96-2)

Development, Implementation and Evaluation of Low-input Crop and Livestock Systems for the Southern Region (88-96-2)

Summary

This ongoing project, coordinated by John Luna of Virginia Polytechnic Institute and State University, consists of three parts: (1) a long-term whole-farm systems study involving crops and livestock, (2) on-farm grazing systems demonstrations, and (3) the development and implementation of a low-input corn production system.

Project Results

Part 1 is a farm-scale experiment designed to compare a conventional crop/livestock system with an experimental, low-input system to produce beef cattle. Involving 48 steers on 80 acres of crop and pasture land, this is the largest low-input farming system comparison study in the US. Conventional livestock production systems in the Southern region rely heavily on harvested forage (mostly alfalfa) and corn produced with heavy dependence on purchased inputs of fertilizers and pesticides. Findings of this study indicate that (1) spring and fall grazing of alfalfa have reduced the need for insecticides to control alfalfa weevil, (2) growing millet before alfalfa reduces the need for herbicides and insecticides, (3) first year corn following alfalfa does not require insecticides for corn rootworm or armyworm control and has reduced N fertilizer needs, and (4) planting alfalfa into tall fescue reduces the need for N fertilizer.

Part 2 is an on-farm grazing systems demonstration project established on a cooperator farm in Southwestern Virginia. Two forage/beef systems are being compared. The first involves rotational and continuous grazing, the use of legumes vs. nitrogen fertilizer. The second involves sequencing of various forage species for year-round grazing. Each system uses 30 cows with their calves and continues the calves beyond weaning through the stocker phase. Four replications of pastures were established in the summer and fall of 1989, including various combinations of tall fescue, alfalfa, and red clover, with and without chemical inputs.

Part 3 involves the development and demonstration of low-input corn production practices, including the use of conservation tillage systems, winter legume cover crops and integrated pest management practices for weeds and insect pests. These on-farm demonstrations were conducted on 14 farms in 1991-1992. Corn production systems being compared include treatments such as use of a rye cover crop mulch, a mixture of hairy vetch and bigflower vetch cover crops, and various levels of N fertilizer application under alternative tillage systems. The no-till system earned a $44 greater net return per acre than that of the disk tillage system. Within the no-till system, the hairy vetch cover crop with no added N fertilizer earned about $22 more net returns per acre than did a rye cover crop with 125 lbs of N fertilizer per acre. These findings augment a growing body of published literature confirming the economic advantages of using winter legume cover crops in corn and other cropping systems.

An experiment involving low-input corn systems evaluated alternative management practices for rye cover crops in no-till corn. Comparisons were made between mowing and conventional herbicide to suppress the rye. Densities of armyworm larvae were estimated from the time of corn seedling emergence until armyworm larvae were no longer found. In four of the five fields in both years, mowing significantly reduced armyworm population densities in the early stages of corn growth. Mowing also adequately suppressed rye cover crop regrowth in all fields. Costs of the cover crop management methods are calculated to be about $6 per acre for mowing versus $10 per acre for paraquat spraying. Averaged across all plots in both years, fields where the cover crop was mowed earned $40/acre more net income than fields where paraquat was used to kill the rye cover crop.

Over the past few decades, "expert systems" computer software has made major contributions in industries like medicine and defense. An expert system is being designed for this project. A prototype computer-aided decision support system called CROPS (Crop Rotation Planning System) has been developed for farm-level planning. This program uses artificial intelligence techniques to generate crop rotation plans for individual farms, implementing low-input sustainable practices and comparing these plans with conventional alternatives. The final version will not only generate crop rotation plans that implement low-input practices; it will also analyze the plans generated and allow the farmer-user to compare the generated plans with an alternative. The system includes simulation models for estimating soil erosion and analysis of the financial status of the farm under various alternative combinations of crop mixes, farm program participation and machinery.

Objectives

(1) Develop and evaluate crop/livestock farming systems that minimize reliance on non-renewable inputs while maintaining or improving profitability, improving long-term soil productivity, and minimizing undesirable environmental impact.

(2) On four cooperating farms, evaluate and demonstrate the role of winter-annual legume/small grain polyculture cover crops in reducing nitrogen fertilizer, herbicide, and insecticide inputs in corn production.

(3) Evaluate the potential of ridge-till systems for corn production in the southeastern United States.

(4) Develop and implement Extension educational programs to promote the adoption of low-input farming technologies, practices, and systems.