CONSERVATION BENEFITS OF THE USDA'S 1983 PAYMENT-IN-KIND AND ACREAGE REDUCTION PROGRAMS

The U.S. Department of Agriculture's 1983 Payment-in-Kind and Acreage Reduction Programs reduced soil erosion on the land withdrawn from production by an average of 1.8 tons per acre per year over the 80 million acres diverted. The erosion reduction could have been significantly greater had the program targeted highly erodible land and had the diverted acres been adequately protected from erosion. Water withdrawal was reduced by 1.6 acre-feet per acre because of diverted lands that would have been irrigated. About 35 percent of the diverted acres provided suitable cover for wildlife. The analysis was based on data from a sample of over 4,900 farms in 278 counties

Nitrous oxide emission from feedlot manure and green waste compost applied to Vertisols

Application of feedlot manure (FLM) to cropping and grazing soils could provide a valuable N nutrient resource. However, because of its high but variable N concentration, FLM has the potential for environmental pollution of water bodies and NO emission to the atmosphere. As a potential management tool, we utilised the low-nutrient green waste compost (GWC) to assess its effectiveness in regulating N release and the amount of NO emission from two Vertisols when both FLM and GWC were applied together. Cumulative soil NO emission over 32 weeks at 24°C and field capacity (70% water-filled pore space) for a black Vertisol (Udic Paleustert) was 45 mg NO m from unamended soil. This increased to 274 mg NO m when FLM was applied at 1 kg m and to 403 mg NO m at 2 kg m. In contrast, the emissions of 60 mg NO m when the soil was amended with GWC 1 kg m and 48 mg NO m at 2 kg m were not significantly greater than the unamended soil. Emission from a mixture of FLM and GWC applied in equal amounts (0.5 kg m) was 106 mg NO m and FLM applied at 0.5 kg m and GWC at 1.5 kg GWC m was 117 mg N2O m. Although cumulative NO emissions from an unamended grey Vertisol (Typic Chromustert) were only slightly higher than black Vertisol (57 mg N2O m), FLMapplication at 1 kg m increased NO emissions by 14 times (792 mg NO m) and at 2 kg m application by 22 times (1260 mg NO m-2). Application of GWC did not significantly increase NO emission (99 mg NO m at 1 kg m and 65 mg NO m at 2 kg m) above the unamended soil. As observed for the black Vertisol, a mixture of FLM (0.5 kg m) and GWC (0.5 or 1.5 kg m) reduced NO emission by >50% of that from the FLM alone, most likely by reducing the amount of mineral N (NH4 -N and NO -N) in the soil, as mineral N in soil and the NO emission were closely correlated

Growth, grain yield and nitrogen use efficiency of Mediterranean wheat in soils amended with municipal sewage sludge

The application of sewage sludge (SS) to agricultural land can improve soil fertility and physical properties, and enhance crop production. This field study was conducted for two consecutive growing seasons to investigate the influence of SS application on winter wheat growth, grain yield, N accumulation, translocation and use, and on trace elements concentrations in soil and wheat plants under Mediterranean conditions. Treatments consisted of three rates of SS, i.e. 20, 40, and 60 Mg dry weight ha(-1) year(-1), one rate of inorganic fertilizer (IF, 120 kg N ha(-1) year(-1) plus 80 kg P2O5 ha(-1) year(-1)), and an unamended control. The application of SS resulted in tall plants with high early dry matter and N accumulation similar to or significantly higher than those obtained with IF. The lowest SS application rate resulted in grain yield similar to that obtained with IF. Nitrogen use efficiency (NUE) in SS treatments was mainly determined by uptake efficiency, which decreased with increasing SS application rate. Values of NUE and biomass production efficiency with the lowest SS rate were similar to those obtained with IF. SS application resulted in increased concentrations of total and DTPA-extractable trace elements in the soil after the first year, but concentrations were much lower than the regulation limits. Concentrations of Cu, Mn and Zn in wheat plants did not exceed those obtained with IF. Overall, SS could be considered for use as a fertilizer in wheat production systems in the area, serving also as an alternative method of SS disposal