Grewia tenax for Sustainable Agroforestry Farming in Saline Soils of Khartoum State of Sudan

Intercropping of cow pea (Vigna unguiculata) with multipurpose tree in terms of Grewia tenax was carried out under saline soils in south of Khartoum State in Sudan. The objectives were to investigate the performance of Grewia tenax trees under sub-irrigation regime in saline soils as well as to find out most agro forestry system suitable for saline soil. The experiment was carried out during period of March to November 2017 in terms of completely randomized block design with 3 replicates. The treatments were Grewia tenax tree that fixed at spacing of 4x4 m versus cow pea crop which sown at one and 1.5 m apart from the Grewia tenax tree trunk at 25 cm and 50 cm as inter and intra rows spacings besides sole Grewia tenax tree and cow pea crop as controls. Soil samples were taken at depths of 0-10 cm, 10-30 cm, 30-60 cm and 60-100 cm from soil profile of 1x1 m and 1.5 m depth and its chemical and physical properties were analyzed.

Grewia tenax trees parameters were measured in terms of tree height, tree collar diameter and tree crown diameter. While cow pea crop parameters were determined in terms of straw weight and crop yield per hectare as well as land equivalent ratio. The data revealed that; soil chemical properties for pH, EC ds/m, CaCo3, SAR and ESP were increased with increasing soil depths , while other chemical properties in terms of Nitrogen content , Organic carbon and C/N ratio did not differ with respect to soil layers. Meanwhile the total average Grewia tenax tree growth means in terms of tree height, tree collar diameter and tree crown diameter were higher under intercropping than in sole trees, similarly for cow pea crop straw weight. Cow pea yield did not differ between the intercropped plots and the control. Partial LER was higher under straw weight than for yield and the total LER was advantageous particularly under GS1 which indicates the superiority of intercropping than mono-cropping in this saline soil.