An evaluation of the impact of different soil management techniques on soil fertility

Abstract

The study is structured in 2 parts. The first part aims to obtain an understanding of the elements which influence soil fertility and how cultivation affects them. It looks at the main macronutrients that are impacted most by cultivation. These being: N, P and K. It also discusses other important variables which one needs to understand and be aware of in relation to soil fertility. The areas covered are organic matter, soil pH and soil salinity. The first part of the study is then concluded by a discussion of those factors which farmers can control and manage to influence soil fertility. The areas discussed are moisture levels and irrigation, tillage and the physical state of soil, the chemical condition of soil and the biological condition of soil. The second part of the study looks at a number of soil characteristics to understand better the effect that different soil management techniques have on soil. Three small plots of land adjacent to each other, carrying the same type of soil but subject to different management techniques were selected and their pH, salinity, organic matter, NO3-, NH4+ and P determined. One plot was used to grow exclusively potatoes over the winter season. A second plot was used to grow fava beans over the winter and spring seasons. In both of these plots there was no crop rotation. A third plot which had never been cultivated was also tested. The plot used for growing potatoes is usually fertilised with rabbit manure. The plot used for growing fava beans is usually fertilised with chemical fertiliser. No fertiliser had been applied since the previous winter. The study confirmed that cultivated soils differ from non-agricultural soil in a number of aspects. The major difference noted related to the organic matter content and the effect that this had on the ammonification and nitrification processes in soil. Noncultivated soil had a higher organic content and a higher amount of ammonium and nitrate available for plants. It was also found that the soil where rabbit manure was applied had high phosphorus levels. With respect to pH level there was no difference between cultivated and non-agricultural soil. Also, cultivated soil had a lower salt content and a slightly higher moisture level. The possible factors contributing to these results are discussed.