ABSTRACT

Lots of wastes are being generated on daily basis and recently, more emphasis is being laid on waste recycling. To verify the hypothesis of study, which stated that organic wastes, irrespective of the source, will enhance the soil properties and yield of groundnut.  A pot trial was conducted at the experimental field of College of Crop and Soil Sciences, Michael Okpara University of Agriculture, Abia-state. The objectives of the study were to investigate the effect of organic wastes on soil properties, potassium forms, yield of groundnut (Arachis hypogaea) and also the best rate of application of the most outstanding treatment among the treatments studied. The treatments comprised of  composted  goat  manure (CGM), composted kitchen residue waste (CKRW), biochar (B), composted goat manure + composted kitchen residue waste (CGM + CKRW),composted goat manure + biochar (CGM +B),composted kitchen residue waste + biochar (CKRW + B) and composted goat manure + composted kitchen residue waste + biochar (CGM + CKRW + B) and the control (no treatment). The treatments were applied at 4tons/ha in the first experiment and 0, 2, 4, 6 and 8 tons/ha of CGM + CKRW + B in the second experiment. The treatments were replicated three times in Completely Randomized Design (CRD). The soil for the experiment was collected from Amaoba in Bende Local government area and the test crop was groundnut (Arachis hypogea) Samnut 23. Pre and post treatment soil analyses were carried out and the following soil properties were determined; Soil pH (water), exchangeable acidity, total nitrogen, available phosphorus, organic carbon, exchangeable calcium, magnesium, potassium, sodium and different forms of K using standard laboratory procedures. Plant parameters measured included plant height, number of leaves, stem girth at 2, 3 ,4 and 5 weeks after planting (WAP) while number of root branching, root  length, number of nodules, number of pods and pod weights were measured at harvest; N, P, K, Mg and Ca uptake of the plant were also calculated. The results obtained showed that  CGM + CKRW+ B increased the soil pH in water from 5.7 before treatment application to 6.4 after planting in the  first experiment while CGM + CKRW+B applied at 6t kg^-1 significantly (P≤0.05) increased the soil pH in water with a value of  5.80 in the second experiment. Available P was significantly  increased (P≤0.05) from a value of 23.7mgkg^-1 before treatment application  to 47.00mgkg^-1  ,while exchangeable Ca was increased from initial value of 2.10cmolkg^-1 to 4.67cmolkg^-1 by CGM+ CKRW +B at the end of the first experiment. Biochar recorded a highest significant (P≤0.05) increase of water soluble K over the other treatments with a value of 0.22cmolkg^-1 while CGM+CKRW significantly (p≤0.05) increased the total K with a value of 0.35cmolkg^-1 over the other treatments. CGM+CKRW+B increased plant height at 5WAP, N and P uptake of groundnut with values of 0.19mg/g, 0.08mg/g and 0.67mg/g respectively in the first experiment. Application of  4tons/ha of CGM+ CKRW+B gave the highest significant (P≤0.05) value for plant height at 5WAP and dry matter yield over the other rates with values of 23.00cm and 7.4g respectively at the end of the second experiment. From the results obtained in the present study, it will be inferred that composted goat manure (CGM) enhanced or fortified with composted kitchen ash /waste (CKRW) and biochar (B) applied at 4tha^-1 significantly improved the productivity of the soil and yield of groundnut in the study area. However a field trial is recommended to ascertain the results.