Farm Scale Evaluation of Alternative Cotton Production Systems

1992 Annual Report for LS92-047

Project Type: Research and Education
Funds awarded in 1992: $60,000.00
Projected End Date: 12/31/1994
Matching Non-Federal Funds: $112,300.00
Region: Southern
State: Texas
Principal Investigator:
William M. Lyle
Texas Agricultural Experiment Station

Farm Scale Evaluation of Alternative Cotton Production Systems


1.) Assemble integrated sustainable cotton production systems consisting of interplanting cotton into cover crops, high residue rotations, conservation tillage, high frequency deficit LEPA irrigation, predictive sequential high frequency fertilizer application and biorational insect control with ultra low volume in-canopy application equipment.

2.) Estimate the risk and environmental impact of the above practices in terms of decreased water and wind erosion, decreased nutrient leaching potential and pest management with environmentally safe chemicals.

3.) Develop an economic model that farmers can use to make decisions concerning the implementation of integrated sustainable production systems.

Dryland and irrigated cropping systems (continuous conventional cotton, wheat-cotton rotation, minimum till continuous cotton, terminated wheat-cotton, sorghum-cotton rotation and cotton-fallow-wheat rotation) were evaluated at the Agricultural Complex for Advanced Research and Extension Systems (AG-CARES) in 1993. Irrigation treatments ranged from very deficit to over irrigation (0.5 ET, 0.75 ET, 1.0 ET and 1.25 ET) based on potential ET calculated from on-site weather data. Sequential fertilizer rates were applied at 70, 85, 100 and 115 percent of the predictive amount necessary for 2-bale yields.

The crop was monitored throughout the season for possible application of various biorational pesticides. When treatable populations failed to develop, this effort was redirected to development and evaluation of a high-speed in-canopy pivot chemigation system with which to effectively apply biorational materials. The cotton stimulation model, Gossym, was also evaluated for simulating cotton development under the different cropping conditions.

All irrigated minimum conservation tillage systems produced higher yields than did conventional tillage. Equivalent yields were obtained with several conservation tillage systems with 25 to 30 percent less water than was required for conventional tillage. LEPA irrigation increased cotton yields by an average of 140 lbs lint/A or 18 percent over traditional spray irrigation. The wheat-cotton cropping system produced the highest dryland cotton yield (553 lbs lint/A) and was more than double the conventional cotton yield (217 lb lint/A). It was found that the current version of Gossym does not provide sufficient flexibility in cropping systems to simulate the impact of various rotations and tillage system.

A significant speed increase (60 ft/min) was accomplished with the high speed pivot and plant coverage with tracers averaged 12 times higher with the experimental system than that of traditional chemigation application. Enterprise budgets were developed for each cropping system and irrigation level and were used in a linear programming optimization model. Depending on the irrigation water availability all optimal solutions included various combinations of the irrigated cotton-wheat and terminated wheat cropping systems and either minimum tillage or cotton-wheat dryland systems.

Optimal solutions of the model never included conventional cotton production practices. In addition to the economic advantages, lower residual nitrate concentrations measured in the root zones of the wheat-cotton cropping systems indicate that these systems along with some degree of deficit high-frequency irrigation and prescription fertilizer application can reduce nitrate leaching potential significantly. This is in addition to decreased wind and water erosion from the high residue rotations.

Two county meetings with total attendance of 85 and two field days with total attendance of about 140 were held to demonstrate the cropping system tests being conducted. In addition, an annual report was prepared and distributed to the area farmers and agribusinesses and also made available to the public through County and District Research and Extension Offices.

Test results support the concept of reduced tillage as a means to conserve moisture, reduce production costs, and increase farm profitability. The positive net returns per acre for all alternative rotational dryland systems compared to a loss for conventional tillage production is economically significant.

The irrigated terminated wheat system, which provides cover during the spring period when potential wind erosion is highest, also produced higher returns per acre than the conventional tillage system, showing that reducing soil erosion while maintaining profitability are both possible. This was reinforced in the optimization model by the fact that conventional cotton production systems were never a part of the optimal solution but only those involving irrigated terminated small grain or rotation with small grain and dryland minimum tillage.

Lower residual nitrates concentrations in the root zone of the wheat/cotton conservation tillage systems indicate that these systems along with some degree of deficit high frequency irrigation and prescription fertilizer application can drastically reduce the potential for nitrate leaching.

Additional improvement and successful testing of a continuous move high speed pivot for ultra low volume chemigation and earlier successful results with a biorational material applied in reduced application volume are very encouraging as to future successful pest control with numerous biorational pesticides

December 1994.