IMPACTS OF APPLICATION OF SOME RAIN WATER MANAGEMENT TECHNIQUES AND YIELD FORECAST OF RAINFED SORGHUM

Abstract

In the dry areas, water, not land, is the most limiting resource for improved agricultural production. Maximizing water productivity, and not yield per unit of land, is therefore a better strategy for dry farming systems. Under such conditions, more efficient water management techniques must be adopted. Water harvesting and conservation are highly efficient practices with great potential for increasing agricultural production and improving livelihoods in the dry rain fed areas. In the drier environments, most of the rainwater is lost by evaporation; therefore, the rainwater productivity is extremely low. Sorghum productivity in rain fed areas of Sudan central clay plains is described as very low due to water scarcity and/or bad water distribution in space and time .This study documents the major research findings regarding improving water productivity in the dry rain fed regions of Sudan by adopting various water harvesting techniques. The study is directed to ascertain the hypothesis that: Productivity of water in rain fed agriculture improved through accelerated uptake and intensive use of rainwater harvesting and water conservation techniques. Hence, this study is directed to compare the performance of different planting geometry: planting on top of tied ridges (PTR), planting in the bottom of ridges (PBR), and flat (FLAT) and broadcasting on corrugations using the conventional wide level disc (WLD) as a conventional method for soil moisture conservation in dry land farming system. To compare the performance of different water conservation tillage: zero-tillage, chisel plow, and the wide level disk as a conventional method. To compare the performance of different In-situ rainwater harvesting and internal (Micro) catchment WHTs: contour ridge (CR), tied ridge (TR), ridge furrow (RF) and wide level disc (WLD) as a conventional method for soil moisture conservation in dry land farming system. To develop, verify, apply and deliver a robust, fully-tested computer model to predict yield, WUE and runoff losses from rain fed farming techniques. The work completed under this study follows on from previous water harvesting projects and research conducted in Twawa at Gedarief University and is linked with current water research. The specific researchable constraint addressed in all of the chapters of this study is the low productivity of water in rain-fed agriculture. A twin-track approach was adopted, in which the fieldwork was linked to computer modeling. The outcome of the modeling effort was the development of the crop growth and water productivity prediction model. The model is a deterministic, process-based physical model with daily time-step cropping systems simulation model. The model can simulate the soil-plant water budget, crop canopy and root growth, and dry matter production for Sorghum crop. The model simulates soil and plant water balance, vegetative growth, root growth and dry matter yield. Crop growth is simulated as a function of radiation intersected by the plant, available water and air temperature. The model considers the relationship between grain yield and seasonal stress index depending on the deficiency in relative evapo-transpiration and plant indexes. The model adds value to the field research in that it gives temporary prediction of the experiment results in a certain location. Also it gives tools that permit planners to make decisions about the best bet for the substitutes of water harvest innovations anywhere. Keywords: Simulation model, Sorghum crop growth; planting geometry; conservation tillage; Rain fed agriculture; Rain water productivity; In-situ rainwater and Micro catchment Water harvesting Techniques.