Assessing the Potential of Organic Wastes as Soil Amendments to Increase Water Retention

Abstract

Water Absorbent Materials are widely proposed for agricultural use with the aim to improve water availability for plants by increasing water holding properties of growing media (soils or soilless substrates). However, commercially found water absorbent materials especially super absorbent polymers (SAPs) are not biodegradable and hence impose environment issues like land pollution. This work aims at assessing the potential of organic wastes as soil amendments to increase water retention. The water retention materials were formulated from polysaccharide rich materials which included sweet potato peels, orange peels irish potato and cassava peels. A small surface area of 2cm pieces of the peels was ensured for ease of carrying out the proceeding activities (drying, fermentation). Sweet potato and irish potato peels underwent fermentation and orange peels boiling for softening.3kg of each of the peels were mixed with 1kg of avocado peels Avocado peels contain oils which prevent clogging when water is poured on the final product. The peels were dried and milled to particle size 250μm. The orange peel based WAM was obtained at this step. The other three underwent gelatinization where after the gel was dried to films which were milled to particle size 250μm and hence WAMs formed. A water retention test was done by measuring the amount of water that was retained by the test sample (30g of the mixture of different WAM to soil ratios. A biodegradability test was also carried out by pouring water on the WAM, putting it in an air tight container and left for a month to see if any growth would appear on it, proving biodegradability. The highest amount of water was retained by the orange peel WAM, cassava peel WAM and sweet potato and Irish potato peel based WAMs in that order. It was also observed that, as the amount of WAM in the soil increased, the water retention of the soil hence increasing the soil’s water retention capacity. The product prepared was found to be biodegradable. It is therefore advisable to use the orange based WAM in the ratios 1:300:60 for WAM (g): water (ml): soil (g) respectively for best results. It was therefore recommended to do more research about how different crops react to different water absorbent materials and how different WAMs perform in a given type of soil.