Moshia, Matshwene Edwin, authorKhosla, Rajiv, advisor2024-03-132024-03-132009https://hdl.handle.net/10217/237883In the western Great Plains of the USA, animal agriculture is an important contributor to the agricultural economy, and many livestock farms are close to water bodies where manure can potentially contaminate the environment. The objectives of the study were to (i) assess the influence of variable rate applications of animal manure on grain yield in continuous maize production fields across management zones (MZs) in dryland and limited irrigation cropping systems, (ii) to study the effects of variable rate application of animal manure on selected surface soil quality parameters across MZs, (iii) to evaluate the variable rate application of manure using environmental risk assessment tools of N leaching and P runoff indices and to understand its impact on environmental quality, and (iv) to evaluate and compare the nitrogen (N) mineralization of variable rates of dairy cattle manure applied on low, medium and high MZs in a controlled environment. To accomplish objectives (i) through (iii), the study was conducted under a continuous maize cropping system on dryland and limited furrow-irrigated fields in northeastern Colorado, USA. For objective (iv), a 120 day laboratory incubation study was conducted. The results of this project indicated that using animal manure alone for maize grain yield production was economically inefficient using enterprise budget analysis. The study suggests that manure can, therefore, be used in conjunction with synthetic N fertilizer to meet crop N requirements at early growth of maize, while animal manure improve soil quality of low productivity soils over time. This can potentially help to limit the amount of N and P lost into the environment. For N mineralization, the study showed a significant difference (P≤0.05) in mineralized N across zones when dairy animal manure treatments were compared. However, N from animal manure does not mineralize differently between low, medium and high management zones. The key in precision manure management was to find a balance between economically, agronomically and environmentally sound manure management strategies across spatially variable soils.born digitaldoctoral dissertationsengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.environmental qualitymanure managementnitrogen mineralizationsoil qualityvariable rate applicationagronomysoil sciencesTextPer the terms of a contractual agreement, all use of this item is limited to the non-commercial use of Colorado State University and its authorized users.