Location: Soil Dynamics Research2013 Annual Report
1a. Objectives (from AD-416):
There is an urgent need to develop organic waste management systems in the southeastern United States that preserve and improve the soil resources and provide for environmental quality. The objectives of this project are to: 1) develop improved management practices and/or technologies for using manures and other byproducts (e.g., FGD gypsum) to reduce nutrient loss to the environment; 2) determine and compare the impacts of poultry litter and fertilizer application practices on atmospheric emissions of greenhouse gases; and 3) in cooperation with other ARS locations, develop and evaluate new technologies (e.g., subsurface banding) for the application of poultry litter in agricultural systems.
1b. Approach (from AD-416):
Application of organic waste to soil can improve soil conditions and provide nutrients needed for plant production. Poultry litter use seems to be a viable option for producers in the Southeastern Region, especially since the bourgeoning poultry industry generates large amounts of manure, and interest in utilizing animal manure as a fertilizer source has increased due to rising costs of inorganic fertilizers. However, improper application of animal manures in agriculture can contribute to environmental degradation such as increased hypoxia, eutrophication of surface waters, human health problems, and greenhouse gas emissions. Because of this growing environmental concern, field and laboratory studies will be established to develop improved methods to utilize waste products for soil and crop benefits while minimizing environmental degradation. In addition, manure’s interaction with tillage and cropping systems is not well understood. Thus, the environmental impact of poultry litter addition to soil must be quantified, and improved management techniques for application need to be developed for sustainable use in agriculture. Studies will be initiated to determine long term effects of poultry litter on plant yields and soil physical properties under various tillage and cropping systems. Different poultry litter application practices, such as subsurface banding, will be evaluated to determine their impact on nutrient loss and greenhouse gas emissions. Soil amendments (e.g., gypsum) will be evaluated to determine the impact on plant responses and the potential to reduce phosphorus (P) loss in runoff. Information acquired in the course of this project will be useful for developing agricultural practices using poultry litter as a nutrient source for environmentally sustainable plant production.
3. Progress Report:
Because of the growing environmental concern regarding organic waste disposal, field and laboratory studies were established to develop improved methods to utilize waste products for soil and crop benefits while minimizing environmental degradation. ARS researchers at the NSDL, Auburn, AL, have initiated a series of field studies in Alabama to evaluate the impact of fertilizer and poultry litter application methods as affected by tillage systems on crop production and greenhouse trace gas losses to the atmosphere. A four-trench litter applicator implement was designed, constructed, and used for applying poultry litter in field experiments. This unique equipment was patented in 2010. Studies utilizing the litter applicator have demonstrated a substantial reduction in phosphorus in runoff compared to surface application of poultry litter. Studies of soil Nitrogen (N) mineralization as affected by microorganism populations and manure handling methods were conducted. Studies on tillage system and fertilizer application methods impacts on greenhouse trace gas emissions were conducted. Experimental evaluations of alternative substrate for use in horticulture container production were studied. Research on microbial-based inoculants has led to a patent for their use in N2O emissions reduction when using urea fertilizers. Research was also conducted on the utilization of gypsum as a soil amendment to reduce Phosphorus (P) losses to the environment from poultry litter applications.
1. Gypsum application reduces soluble Phosphorus (P) losses to the environment from poultry litter applications. There are growing concerns regarding the fate of nutrients, especially P, from land application of animal waste. One approach to reduce runoff losses of P is to treat manure or the soil receiving manure with chemical amendments such as gypsum. A study using rainfall simulations to examine the impact of flue gas desulfurization (FGD) gypsum application on runoff nutrient losses on a Coastal Plains soil was conducted. Four rates of FGD gypsum (0, 2.2, 4.4, and 8.9 Mg ha-1) were applied to plots of coastal bermudagrass, which had received application of 13.4 Mg ha-1 poultry litter. Plots with FGD gypsum but no poultry litter and plots with no litter or FGD gypsum were also utilized. Rainfall simulation was used to generate water runoff for 60 min and samples were analyzed for dissolved reactive P (SRP) and other total and soluble elements. Heavy metals were also analyzed. Results indicated a 51% reduction in total SRP load with the application of 8.9 Mg ha-1 FGD gypsum. Measurement of heavy metals in runoff where all found to be below detection limits. The results indicate that use of FGD gypsum on pastures receiving poultry litter in the Coastal Plains would be an effective method of reducing SRP losses to the environment.
2. Effects of tillage systems and fertilizer application methods on greenhouse gas emissions were studied. Tillage and fertilization practices used in row crop production are thought to alter greenhouse gas emissions from soil. Research was conducted to determine the impact of fertilizer sources, land management practices, and fertilizer placement methods on greenhouse gas (CO2, CH4, and N2O) emissions. A new prototype implement developed for applying poultry litter in subsurface bands in the soil was used in this study. Measurements of greenhouse gases were measured to assess the effects of different tillage (conventional vs. no-tillage) and fertilizer placement (subsurface banding vs. surface application) practices in a corn cropping system. Fertilizer sources were also studied. Banding of fertilizer resulted in the greatest concentration of gaseous loss (CO2 and N2O) compared to surface applications of fertilizer. Conventional tillage practices also resulted in a higher concentration of CO2 and N2O loss. These results suggest that poultry litter use and banding practices have the potential to increase greenhouse gas emissions.
3. Developed alternative greenhouse substrate component for annual bedding plant production. Traditional substrate (pine bark) for greenhouse production in the horticulture industry is becoming increasingly scarce, increasing the expense of its utilization. Studies were conducted with Auburn University in Auburn, AL, to evaluate wood based products as an alternative greenhouse substrate component for horticulture plant production. Wood based substrate was compared to traditional greenhouse substrate to grow woody ornamentals nursery crops. Similarities among treatments in these studies indicate that wood based substrate is a potentially viable substrate option for use as a component/replacement for pine bark or peat moss in nursery production.
4. Increases in atmospheric concentrations of nitrous oxide (N2O) from agricultural soils are attributed to excessive applications of nitrogen (N) fertilizers. Thus, new nutrient management strategies are needed. Research has been conducted to test the hypothesis that microbial-based inoculants known to promote root growth and nutrient uptake will reduce emission of nitrous oxide in the presence of nitrogen fertilizers under controlled conditions. The microbial based treatments were SoilBuilder (SB), a metabolite extract of SoilBuilder (SBF), and a mixture of four strains of plant growth-promoting Bacillus spp. Experiments included two different N fertilizers: urea, and urea ammonium nitrate (UAN) 32% N and a no-fertilizer control. After 29 days of incubation, cumulative emissions of N2O were reduced 80% (SB) and 44% (SBF) in soils fertilized with UAN. Treatment with Bacillus significantly reduces nitrous oxide production at 1 and 2 days of incubation in soils fertilized with UAN. Microbial-based treatments did not reduce N2O emissions associate with urea application. Overall, the results demonstrated that microbial-based inoculates can reduce emissions of N2O associated with N fertilizer application, and the response varied with the type of microbial inoculant and fertilizer.
Nyakatawa, E.Z., Mays, D.A., Way, T.R., Watts, D.B., Torbert III, H.A., Smith, D.R. 2012. Soil carbon dioxide fluxes in conventional and conservation tillage corn production systems receiving poultry litter and inorganic fertilizer. Journal of Sustainable Agriculture. 36(8):873-892.