Cattle manure increases soil weed population and species diversity in a semi-arid environment

Abstract

This study investigated the quality of available cattle manure resources in selected villages of the North West province and its influence as a weed seed source when applied to soil. Analysis of manure samples showed a large variation in the quality of manure between seasons and between villages with respect to nitrogen, phosphorus, moisture and soil content. Apart from the obvious seasonal weather differences, the variations were attributed to management of the manure in terms of feed quality, storage and corralling practices. When mixed with soil, the manure significantly (P <0.05) increased both the population (from seven to 24 times) and number of species of weed seedlings in all the villages during both summer and winter seasons. The most abundant weeds were Eleusine coracana, Cynodon dactylon and Eragrostis lehmanniana, while Dactyloctenium australe, Sporobolus nitens, Tagetes minuta and Malva parviflora were the least abundant. Grass species were more prevalent in the manure amended soils than broad-leaved weeds in all the villages and seasons. It was concluded that manure application to soil contributes to the problem of weeds in crop fields and that strategies of managing cattle manure designed to reduce the number and species of weed seeds need to be adopted.