Mineralization studies are the first step in determining the usefulness of an amendment such as fertilizer, and are essential to creating guidelines for dairy waste management to help producers make informed decisions. Our goal was to assess the effects of dairy raw, composted, and digested manure amendments on C, N, and P mineralization to evaluate the feasibility of their in-farm production and use as organic fertilizers. The liquid and solid fractions of dairy effluent (LDE, SDE), dairy effluent digestate (DED), onion–cattle manure digestate and compost (OCMD, OCMC) were characterized by chemical and spectroscopic methods. Soil microcosms with LDE, SDE, DED, OCMD and OCMC and the C, N and P mineralization were determined periodically. Elemental and structural differences among amendments led to contrasting profiles of C, N, and P mineralization, and thus to differences in nutrient availability, immobilization, and CO2 emission. All processed materials were more stable than untreated waste, reducing C emissions. Digestates showed net C immobilization, and supplied the highest levels of available N, creating a relative P deficit. Instead, the compost supplied N and P via mineralization, producing a relative P excess. Future studies should aim at evaluating fertilization strategies that combine both kinds of amendments, to exploit their complimentary agronomic characteristics.
Composted manure is the greatest nitrogen (N) source in organic agriculture, where the use of chemical fertilizers, except the use of rock phosphate as P source, is not allowed. The aim of this study was to evaluate the effect of the soil type and compost characteristics on the potential rates of mineralization and on the kinetics of the nitrogen (N), phosphorus (P), and carbon (C) release patterns. For this, an aerobic incubation study was conducted over the course of 119 days at 25 °C using two different composts as amendments: a compost from biosolids and wood shavings (CRUB), and a compost from poultry manure with wheat straw (CSP). The composts were incorporated into two different soils of contrasting texture, sandy loam (S1) and silty clay loam (S2), at the dose of 160 kg N ha−1. Samples were collected eight times during the incubation period. The N and C dynamics were studied separately according to the different soil type. In both soils, a predominance of the nitrification process immediately after compost application was observed, showing a higher mineralization in the sandy loam soil, this trend being followed by a decrease and even an immobilization process, associated with stable organic materials such as compost. Moreover, both composts presented high contents of available P, but without exceeding 50 mg P kg−1, due to the slow release from the stable organic P fractions present in compost. The results obtained showed that despite the initial mineralization, both composts showed a significant period of N immobilization after their application into the pampean soils, which makes it necessary to anticipate their incorporation to avoid this lack period for crops. Furthermore, the application of these composts to the pampean soils implied an incorporation of available P, but with a slow release that avoided overfertilization, but also reducing N:P ratio and producing a relative deficit of N. Therefore, the results obtained suggested that it is necessary to study nutrient mineralization processes of the amendments prior to their use, according to the edaphoclimatic condition of each crop, in order to predict the release dynamics on soils and the fertilization potential to minimize potential environmental impacts.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.