Location: Soil Dynamics Research2011 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. We have initiated a series of field studies in Alabama (including the Sand Mountain region) 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 microorganism populations as affected by soil properties and landscape position as well as the potential for plant growth-promoting rhizobacteria to improve nitrogen fertilizer uptake were conducted. Research was also conducted to evaluate composted poultry litter as an amendment with pine bark, WholeTree, and clean chip residual substrates for use in horticulture container production.
1. New application technology to subsurface band poultry litter reduced nutrient losses in runoff. Use of poultry litter as a soil amendment often results in excessive nutrients loading in runoff waster. ARS scientists at the USDA-ARS National Soil Dynamics Laboratory (NSDL) recently developed an experimental implement to subsurface band poultry litter in soil. Use of this implement to subsurface apply poultry litter in soil can potentially reduce the negative impact that nitrogen (N) and phosphorus (P) loss from poultry litter has on water quality. Rainfall simulation study were performed to evaluate how subsurface applying poultry litter in a bermudagrass pasture would impact nutrient loss in surface water runoff at two field sites containing soil from the Piedmont and Coastal Plain regions of the southeastern U.S. Subsurface banding of poultry litter was compared to surface applied poultry litter, inorganic fertilizer, and a nonfertilized control. Subsurface banding poultry litter reduced the impact of N and P loss in surface water runoff to levels observed in the non-fertilized pasture.
2. Soil microbial community dynamics are influenced by soil properties and landscape position. Microbes are responsible for supplying the soil with plant available nutrients when using manure as a fertilizer source. ARS scientists at the USDA-ARS National Soil Dynamics Laboratory (NSDL) conducted to evaluate how soil microbes are affected by manure addition, season of the year, and differences in slope and soil types. Addition of dairy compost increased the activity of the microbes compared to soil without dairy compost. Soil microbes were more active in the summer season compared to the winter season. Slope and soil type affected microbial activity with the loam soil located in a depressed area having the greatest impact on microbial activity. A sandy loam soil located at the top of the slope had the least amount of activity. An evaluation of the microbial community showed that a change in the type of microbe also occurred. When land managers are using manure as a source of plant nutrients, season and slope of a field and soil type should be considered.
3. Plant growth-promoting rhizobacteria improved plant uptake of nitrogen. It has been demonstrated that plant growth-promoting rhizobacteria (PGPR) can potentially promote plant growth. It has been speculated that one of the mechanism for this increased plant growth is stimulated nitrogen (N) uptake by plant roots exposed to PGPR. Specifically, it is believe that the increased plant N is a result of increased fertilizer N utilization efficiency. ARS scientists at the USDA-ARS National Soil Dynamics Laboratory (NSDL) conducted studies using 15N isotope techniques determine that PGPR could enhance plant uptake of N. Results showed that the dry biomass and N uptake in plants which received 70% to 90% of recommended N fertilizer with PGPR inoculation was comparable to plants that received full rates of fertilizer without PGPR. These results indicate that application of PGPR could be used to reduce fertilizer N application needed for crop production.
4. New method to calculate greenhouse gas flux from soil following band application of manure were developed. Concerns about climate change have generated interest in evaluating impacts of land use practices on greenhouse gas emissions. Also, another negative consequence of greenhouse gas emissions from soil is the detrimental impact on soil quality from the loss of nitrogen and carbon from soil. Band application of manure and fertilizer is a method of applying these materials in narrow bands, either on the soil surface or beneath the soil surface. Gas flux chambers are commonly used by researchers in determining emissions of greenhouse gases from soil, but calculations of average gas fluxes emitted from a field area are more complex for band application than for broadcast application of manure or fertilizer using these chambers. ARS scientists at the USDA-ARS National Soil Dynamics Laboratory (NSDL) developed a new method for calculating average gas fluxes emitted from a field area to which manure or fertilizer has been applied in bands. This method is expected to be useful in quantifying greenhouse gas emissions from fields to which manure or fertilizer has been applied in bands, either on the soil surface or in subsurface bands.
5. Turning wood industry waste into nursery growing media. WholeTree (WT) and Clean Chip Residual (CCR) are potential new nursery substrates that are byproducts of the forestry industry containing high wood content. Initial immobilization of nitrogen is one concern when using these new substrates; however the addition of composted poultry litter (CPL) to substrates containing high wood content could balance initial nitrogen immobilization and provide an inexpensive fertilizer source for growers. ARS scientists at the USDA-ARS National Soil Dynamics Laboratory (NSDL) conducted experiments on alternative substrate including poultry litter in the nursery production. Results indicate that these species can be grown in WholeTree and clean chip residual substrates 6:1 (v:v) with composted poultry litter. Use of composted poultry litter in WholeTree and clean chip residual substrates could provide an alternative to traditional pine bark and peat based combinations in container production while providing poultry producers an environmentally sound means of waste disposal.
6. Wood industry waste can be used to extend pine bark supplies as a growing media. With the recent decline of available pine bark (PB) supplies, and the threat of continued decline, nursery growers have begun seeking possible alternatives or amendments for their standard growing media. WholeTree substrate (WT) and clean chip residual (CCR) are two possible substrate alternatives with commercialization possibilities. Experiments conducted by ARS scientists at the USDA-ARS National Soil Dynamics Laboratory (NSDL) shows that with most species, nursery producers could amend their PB with up to 75% WT or 75% CCR with limited impact on crop growth. This information will allow growers to develop plans for extending existing PB supplies with WT or CCR.
Watts, D.B., Way, T.R., Torbert III, H.A. 2011. Subsurface application of poultry litter and its influence on nutrient losses in runoff water from permanent pastures. Journal of Environmental Quality. 40(2):421-430.