Influence of Various Composted Organic Amendments and Their Rates of Application on Nitrogen Mineralization and Soil Productivity Using Chinese Cabbage (Brassica rapa. L. var. Chinensis) as an Indicator Crop

Abstract

There is a diversity of locally available nitrogen (N)-rich organic materials in Samoa. However, none of them was evaluated for their N supplying capacity after composting in Samoan Inceptisols for vegetable cultivation. Thus, N-releasing capacity of five composted organic amendments (OAs) namely macuna, gliricidia, erythrina, lawn grass and giant taro, and their two application rates (10 and 20 t ha−1) were assessed through a laboratory incubation and a crop response study using Chinese cabbage as a test crop. Among the OAs, composted mucuna was characterized by a higher total N (2.91%), organic C (63.6%) and NO3−N content (341 mg N kg−1). A significant difference in N mineralization was observed among the OAs as well as application rates. The highest N mineralization was recorded in composted mucuna followed by gliricidia, erythrina, lawn grass, and giant taro. A crop response study also showed a similar trend. Mucuna treatment had the highest biomass yield and N uptake followed by gliricidia, erythrina, lawn grass, and giant taro. Leguminous composted OAs @ 20 t ha−1 performed substantially better in all the plant growth and yield parameters, and N uptake compared to 10 t ha−1 that was not the case for non-leguminous OAs. Thus, non-leguminous OAs should be applied at 10 t ha−1. All the composted leguminous OAs showed promising results while mucuna was the best in both the application rates. Therefore, mucuna can be promoted to supply N for crop cultivation in Samoa, other Pacific Islands and tropical countries where N fertilizer is costly and not easily available.

Nanobiochar Associated Ammonia Emission Mitigation and Toxicity to Soil Microbial Biomass and Corn Nutrient Uptake from Farmyard Manure

“…Nutrient accessibility in the soil for crop uptake from organic fertilizers is solely dependent on the presence and activity of soil microorganisms and fauna [64][65][66]. When organic fertilizer is applied to the soil, it undergoes microbial and soil faunal colonization [67,68] that determines the decomposition and nutrient mineralization-immobilization turnover [69] and thereby, nutrient accessibility for crop uptake [70]. The application of high doses of nanomaterial in the soil caused toxicity to the soil microorganisms and fauna [71,72] and thereby reduced the organic amendments' decomposition and nutrient mineralization and eventually, the crop yield [29,30].…”

Nutrient Release from Vermicompost under Anaerobic Conditions in Two Contrasting Soils of Bangladesh and Its Effect on Wetland Rice Crop

“…All the data regarding mineralized/released nutrients were fitted to a first-order kinetics model to estimate mineralization and/or nutrient release rate using IBM SPSS version 22 (Chicago, IL, USA). The model is: N(t) = NA (1-exp(-kt)), where t is the time (in week), N(t) is the amount of mineralized/released nutrients, NA is the potentially mineralizable/releasable nutrients in mg kg −1 soil and k is the first-order rate parameter (mg kg −1 soil wk −1 ) as adopted by Kader et al [50,62] and Suruban et al [67]. All the collected plant growth parameters and yield data were subjected to statistical analysis using the computer package program of MSTAT-C [68].…”

Soil mineral nitrogen regulation by a novel porous material in structurally degraded soils

“…Ruamps et al 55 suggested that a soil porosity of 30 to 100 μm is more beneficial to soil microbial activities, and organic matter decomposed more, leading to the variable release of initial soil mineral N. In addition, the N mineralization rate k in our study (0.08-0.11 mg N kg −1 soil d 1 ) was much lower than that reported in a previous study (0.2-0.6 mg N kg −1 soil d −1 ). 56 This difference might be due to the various kinetic models. The previous study used a zero-order kinetic model, but we used a first-order kinetic model.…”