|NETTHISINGHE, ANNESLY - Western Kentucky University|
|GILFILLEN, BECKY - Western Kentucky University|
|WILLIAN, TODD - Western Kentucky University|
|ROWLAND, NAOMI - Western Kentucky University|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2010
Publication Date: 1/1/2011
Citation: Netthisinghe, A., Gilfillen, B., Willian, T., Rowland, N., Sistani, K.R. 2011. Inorganic fertilizers after broiler litter amendment reduce surplus nutrients in orchardgrass soils. Agronomy Journal. 103:1-8.
Interpretive Summary: Broiler litter is a good source of plant nutrients and as a soil amendment; it contains substantial amounts of nitrogen (N), Phosphorus (P), Potassium (K) and other nutrients needed by crop. Research studies have demonstrated that broiler litter can be an effective source of nutrients that can enhance forage biomass production. In manure disposal efforts, producers often broadcast apply broiler litter at high fixed rates or rates based on crop N requirement to supply plant nutrients, particularly N and P. However, long-term broiler litter application at high rates for forage production can result in P and other micronutrients like copper (Cu), iron (Fe), and zinc (Zn) accumulation, which hinder crop growth, limits further broiler litter use, and can pose adverse environmental impacts related to soil and water quality. Also run off water from manured pastures and hay fields can serve as a nutrient transport source to surrounding ecologically sensitive surface water bodies causing water quality degradation. However, despite potential risks, land application offers the most practical and economical mean to manage large quantities of broiler litter. The main objective of this study was to determine how different broiler litter amendment regimes contribute to soil nutrient accumulation and if inorganic fertilizer applications after cessation of broiler litter amendment would reduce surplus soil nutrients. Results showed broiler litter application based on N requirement of crop led to elevate soil P, Cu, and Zn contents substantially from the initial levels. Implementing an alternative cycle of inorganic fertilizer application can reduce P, Cu, and Zn levels. An alternative cycle of inorganic fertilizer application after broiler litter amendment can be recommended as a best management practice to remediate surplus soil nutrients in highly broiler litter impacted soils while assuring high forage production benefits.
Technical Abstract: The common producer practice to dispose of broiler litter at high rates to forage crops allow excessive accumulation of soil nutrients. A remediation study was developed to examine if inorganic fertilizer application over the residual fertility of broiler litter would reduce surplus soil nutrients in orchardgrass (Dactylis glomerata L.) soils and to study the resulting biomass production. Three remediation treatments; inorganic fertilizer on antecedent broiler litter at the N rate (R-PLN), P rate (R-PLP), P rate with inorganic N(R-PLP+N), and inorganic fertilizer (INORG) were tested and results were compared with broiler litter at N rate (PLN) P rate (PLP), and P rate with inorganic N (PLP+N). Repeated broiler litter application at N rate led to elevate soil P, Cu, and Zn contents > 200% from the initial levels. Implementing an alternative cycle of inorganic fertilizer application can reduce P, Cu, and Zn levels respectively by 32 mg P kg-1 yr-1, 1.9 mg Cu kg-1 yr-1, and 2.4 mg Zn kg-1 yr-1. Remediation by inorganic fertilizer application may take at least five years to reduce P, Cu, and Zn levels back to the normal range. In addition, inorganic fertilizer application over broiler litter at N rate can offer similar forage production as inorganic fertilizer and N rate broiler litter amendment. An alternative cycle of inorganic fertilizer application after broiler litter amendment can be recommended as a best management practice to remediate surplus soil nutrients in highly broiler litter impacted soils while assuring high forage production benefits.