Effects of cropping systems on soil quality and carbon sequestration potential in Kauwi and Nombe wards of Kitui County, Kenya

Abstract

The use of incorrect agricultural methods and utilization of land, excessive inorganic chemical applications, misguided cultivation, and nutrient mining have all contributed to a considerable deterioration in soil health globally. These factors have resulted in bad soil quality. Soil quality decreases as a result of the adoption of agricultural management practices that farmers have relied on as supplements or replacements for biological functions. This research aimed to determine the geographical and seasonal variation of soil quality under different cropping systems in the Kauwi and Zombe wards of Kitui County, as well as the soil carbon sequestration potential of these systems. Since no attempts were made to influence the outcomes of the study's variables, a descriptive research strategy was used. Vegetable, cereal, fruit, and agroforestry-based cropping systems were chosen on purpose in both the Kauwi and Zombe wards. As a comparison, uncultivated land was chosen as control. During the typical long (MAM) and short (OND) rainfall seasons, composite soil samples were taken from the cropping systems at random. The treatments consisted of five identical sets of the chosen systems planted in the farmers' fields. The OPSTAT statistical analysis tool was used for data coding and analysis. Soil pH and Soil organic carbon were shown to be significantly affected by the interplay between cropping strategies and locations. Zombe's vegetable cropping strategy resulted in the lowest soil pH and electrical conductivity values. Under a vegetable-based cropping scheme, soil organic carbon and NPK were likewise shown to be greatest in Zombe ward. Soil bulk density varied between 1.66 and 1.56 Mg m-3 in Kauwi and between 1.66 and 1.80 Mg m-3 in Zombe, according to the analysis of spatial variation. Significant differences were seen in soil pH, EC, carbon, and NPK across cropping systems and wet/dry periods. Greater carbon stock (95.52Gg C) was found in the Zombe ward, which corresponded to a greater carbon density (4.55 Mg C ha-1) under vegetable-based cropping system followed by Agroforestry (36.53Gg C). As a result, the maximum capacity to sequester soil carbon was found in the vegetable-based cropping system, regardless of the location, as measured by carbon density, in both the Zombe and Kauwi wards. Because of the high retention of carbon rates achieved by vegetable and agroforestry cropping systems, governments at all levels should educate and encourage farmers to switch to these methods in order to improve soil quality and mitigate effects of climate change.