International Journal of Science and Research (IJSR) ISSN: 2319-7064 ResearchGate Impact Factor (2018): 0.28 | SJIF (2018): 7.426 Volume 8 Issue 12, December 2019 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Cowpea (VignaUnguiculata) Fast Establishment Enhances its Potential for Food Security and Short- Term Rotations in Semi-Arid Areas in a Changing Climate Jacinta M. Kimiti Department of Environmental Science and Land Resources Management; School of Environment, Water and Natural Resources; South Eastern Kenya University (SEKU). P.O Box 170-90200, Kitui, Kenya Abstract: Cowpea (Vignaunguiculata L. Walp.) is a drought resistant, multipurpose legume commonly used for food, fodder and soil fertility improvement. Cowpea and commonly cultivated multipurpose shrubs (Calliandracalothyrsus and Leucaenaleucocephala) were evaluated for their early growth establishment abilities by assessing nodulation, shoot and root biomass, root to shoot ratios and total plant biomass. The main objective of the study was to investigate how cowpea early growth compares with that of commonly grown multipurpose leguminous tree shrubs and assess the potential of the test plants for use in short term rotations in semi-arid areas. The experiment was laid down as a completely randomized block design replicated five times. Results obtained indicated that cowpea maintained higher values for all parameters measured in the test plants throughout the sampling period. For instance, cowpea accumulated highest shoot biomass of 1.2g compared to 1.08g and 1.04g accumulated by Leucaena and Calliandra, respectively. Root biomass was also highest for Cowpea 1.5g, followed by Leaucaena 1.2g and finally Calliandra. 0.9g. Cowpea root to shoot ratio was significantly (p<0.05) higher than that of Calliandra. These results indicated that cowpea could be a potential short rotation legume for cropping systems in the semi-arid areas in a changing climate. Keywords: Biomass, Cowpea, Early growth, Nodules, Short rotations 1. Introduction Crop yields in Sub-Saharan Africa are currently low ([1]).The commonest constraints facing crop production in most parts of Sub-Saharan Africa includes soil nutrient deficiencies, soil physical constraints, pests and diseases as well as soil fertility management practices ([2], [3],[1]). Low soil fertility results from loss of soil organic matter because many farmers, especially smallholders, carry out farming practices which discourage organic matter accumulation in the soil. Such practices includes continuous cropping, removal and or burning of weeds, cutting and carrying off- farm of crop residues to feed livestock, overgrazing on the farms during the long dry spells, soil erosion by water and wind, and little or noaddition of organic or inorganic inputs to replenish soils ([4], [5]). Lack of organic inputs, which ties mineral elements into the soil, reduces the soil ability to respond to inorganic mineral fertilizers. Studies have shown that combination of both organic and inorganic inputs have synergy and cause crops to perform better than either organic or inorganic fertilizers when singly added ([6], [7], [8]). Disadvantages of low fertility soils includes low agricultural yields, food insecurity, uneconomical agricultural investments, increased food prices, and reduced government revenue from agricultural produce ([9], [10]). This calls for sound soil management practices to enhance soil fertility and boost yields. Farmers in Sub-Saharan Africa havehistoricallyused livestock manure to counter nutrient depletion and hence increase crop yields ([11],[12], [13],[14], [15], [16],[17], [18]). However, livestock manure are usually inadequate and vary in nutrient content depending on livestock feed and manure collection and storage methods ([18], [19], [20]).Fertilizers are also used but their use is limited by their high costs, scarcity, and cultural beliefs especially in developing countries ([21], [14]). Therefore, there has been continuous search for alternative and sustainable sources of soil nutrients especially nitrogen ([21], [22]). Studies on the use of leguminous plants to enhance soil nutrient are common ([23], [24], [25], [26]). These studies showed that leaves of leguminous plants release nutrients which can beused as mulches to enhance crop growth. This study therefore sought to investigate fast-establishing and growing multipurpose legume which in its early growth can provide high leafbiomass for food and soil fertility enhancement in the current changing climate in the semi-arid areas. In this study a comparison of early growth of commonly used leguminous shrubs for soil enrichment with that of a commonly cultivated drought resistant and fast growing grain legume, cowpea, was made. The ultimate goal was to establish which of the legumes can offer an option for short rotation mulches for enhanced soil fertility in the semi-arid areas of south eastern Kenya in the current changing climate. 2. Materials and Methods This study was conducted at The South Eastern Kenya University, main campus tree nursery. The university is located in Kitui County along machakos-Kitui road, 15 km off Kwa-vonza shopping center in a semi-arid environment at Geographycal positioning 01.313358 o S, 037.75546 o E and 01.31422 o S, 037.75576 o E, 1173 m above sea level. Seeds of leguminous shrubs were obtained from Kenya Forest Research Institute (KEFRI) while cowpea seeds were obtained from South Eastern Kenya University farm. Clean undamaged seeds were soaked in hot water overnight and later pregerminated in water agar. As soon as the seedlings Paper ID: 28111901 DOI: 10.21275/28111901 849