Effects of Fruit and Vegetable Wastes and Biodegradable Municipal Wastes Co-Mixed Composts on Nitrogen Dynamics in an Oxisol

Abstract

Organic waste generation in developing countries is increasing and appropriate disposal methods are needed. An open aerobic composting using 20 L bins was carried out using 6 composts made using ratios of 3:1, 1:2 and 1:4 fruit and vegetable wastes (FVW):biodegradable municipal waste (BMW), with and without addition of homemade indigenous microorganisms (IMO), for 30 days to monitor compost quality. The nitrogen contents of the composts ranged from 1.52 to 2.76% N equivalent to 76–138 kg N ha−1 at 5 t ha−1 compost application rates. Heavy metals measured were below permissible levels of compost quality standards. Selected composts were incubated for 60 days to study nitrogen mineralization dynamics when applied to an Oxisol at the rates of 0, 5 and 10 t ha−1. The results showed significant differences (p ≤ 0.05) in the amounts of NH4-N, NO3-N and cumulative NH4-N + NO3-N released. Ammonium nitrogen released was higher on days 3, 21 and/or 40 for composts 3:1 − IMO at 10 t ha−1, 3:1 + IMO at 10 t ha−1 and 3:1 − IMO at 5 t ha- 1. Cumulative N (NH4 -N + NO3 -N) released over control were 77.98, 64.09 and 64.35% higher for application of 3:1 + IMO, 1:2 − IMO and 1:2 + IMO, respectively, at an application rate of 10 t ha−1. The increased nitrogen content, low heavy metals concentrations and the amount of mineralized N from the composts exhibit potential for increased nutrient availability when applied to a soil.

Chemical and Microbial Characterization of Washed Rice Water Waste to Assess Its Potential as Plant Fertilizer and for Increasing Soil Health

“…In addition, however, the decrease in the N corresponded to the increase in the NH + 4 -N and NO − 3 −N content (Figure 3), which agrees with Neina [48] who reported that N can be converted to NH + 4 and NO − 3 during mineralization. A concurrent decrease in WRW pH with an increase in NH + 4 -N and NO − 3 −N observed in this study agrees with Musa et al [49], where they reported a negative relationship between nitrate production and the pH of the soil. In this study, the higher the W:R ratio, the greater the pH, and the longer the fermentation, the lower the pH.…”

Carbon Dynamics of Fruit and Vegetable Wastes and Biodegradable Municipal Waste Compost-Amended Oxisol

“…Better conditions for microorganisms and microbial activity are positive beyond the productive function of soil as they will increase biodiversity and influence the biogeochemical cycles that are dependent on organic matter decomposition [46,48]. Heavy metals from composts can inhibit dehydrogenase enzyme activity [6]; however, the compost heavy metals from the present composts used have been reported to be low beyond detection limits [27]. Dehydrogenase activity was reported to be higher at lower compost application rate of 20 Mg ha −1 than 80 Mg ha −1 , and it was attributed to the toxic effect of heavy metals at the higher compost application rate and the heavy metal content of the composts used [49].…”

“…It can be observed from the above results that compost functional group development can be attributed to the substrates used in making it. Composts 3:1, irrespective of IMO addition, had more pronounced functional groups located on 3347 cm −1 , 3274 cm −1 (3:1 −IMO) and 3344 and 3281cm −1 (3:1 +IMO) probably due to the ratio of fruit and vegetable wastes in the compost formulation [27] while in addition, compost 3:1 +IMO had an additional functional group located at 2932 cm −1 , possibly obtained because of the ratio of FVW used in the composting and the additional microorganism source due to the addition of indigenous microorganisms (IMO).…”

“…The mixture was mixed and kept in an airtight opaque container and opened daily to release suppressed carbon dioxide. It becomes ready for use after 3-5 days when the pH reads 3.5 and it released a sweet-sour smell [27]. The IMO was used as a source of moisture during the composting process, and 0.5 and 2 litres were added to composting ratios 3:1 and 1:2, respectively.…”

“…Composts at varying mixture ratios of 3:1 and 1:2 of FVW: BMW with and without IMO, as detailed in Table 1 and prepared by Musa et al [27], were taken and applied at the rates of 0, 5 and 10 Mg ha −1 to a Munchong series soil (Oxisol). An amount of 100 g of previously sieved Munchong series soil was weighed and placed into a glass jar, distilled water was added to it to reach 60% field capacity and the weight was noted.…”