Long-term effect of CQA-tested municipal solid waste compost application on soil health and crop productivity

Various types of solid waste composts have been applied in food crop production and their effects on both crops and environment reported. Compost quality alliance (CQA)-tested municipal solid waste (MSW) compost has not been evaluated for its ability to improve soil health and safe plant food productivity. This research was conducted to find out the effects of CQA-tested MSW compost on soil health and plant productivity, when applied to soils over an extended period of time and at different frequencies of application. CQA-tested MSW compost was applied annually and biennially at a rate of 763.44 m3 ha-1 to soils in experimental plots laid out in completely randomized block design (CRBD). Control plots did not receive CQA-tested MSW compost treatment. Effects of the frequency of CQA-tested MSW compost application on soil health, crops growth rate and produce nutritional quality was assessed. The results indicate that CQA-tested MSW compost application improved the physicochemical and hydrological properties of the soil, with annual application of the CQA-tested MSW compost producing the best results in each case of the physicochemical and hydrological parameters analyzed. Except for lettuce, growth and functional traits of crops were more improved when CQA-tested MSW compost was applied annually than biennially or the control. CQA-tested MSW compost application did not significantly (p > 0.05) affect the maximum quantum efficiency of PS II in the crops. The total organic acids, glucose, total acylcarnitine and total phospholipids contents of crop edible portions were dependent on soil treatment with CQA-tested MSW compost. Annual and biennial applications of the CQA-tested MSW compost influenced the putrescine and spermidine but not the spermine contents in crop edible portions. Amino acid contents in edible portions of the crops were improved by CQA-tested MSW compost application to soils. Results of the mineral profile of the crop edible portions showed that application of CQA-tested MSW compost to soils improved the contents of nutritional minerals and did not cause accumulation of potentially toxic elements (PTE) beyond the international standards of acceptable limits in foods. In overall, application of CQA-tested MSW compost to soils over a period of five planting seasons, improved the nutritional quality of crops edible portions and soil health indicators, without causing a negative impact on the soil. From the results of the application of CQA-tested MSW compost to soils, on soil health and crop productivity, sustainable horticultural food crop production could be archived; thereby reducing the problem of food insecurity.