Legumes Improve Wheat and Maize Productivity Grown in Different Cropping Systems Under Changing Climate

Diversification of agricultural cropping systems is known to be a significant strategy to accomplish the ecological intensification and enhancing sustainability. This chapter composed of two sections. In the first section, we tested the capability of SALTMED model to simulate multi-year crop sequences of maize and wheat, as well as simulation of the inclusion of legume crops, namely fahl clover and cowpea within the system of maize and wheat in Egypt. The SALTMED model was calibrated and validated using data of a two-year field experiment for three crop sequences for maize and wheat in sandy soil: CS1, which represent the traditional practice by the farmers (maize-fallow-wheat), and involved low water and fertilizer use efficiency. The other two crop sequences implemented irrigation scheduling and fertigation: CS2 (maize-fahl clover-wheat) and CS3 (cowpea intercropped with maize-fahl clover-wheat). The results indicated that the SALTMED model was successful in simulating the yield of the studied crop sequences, with high degree of accuracy. The model also simulated nitrogen uptake by the studied crops, as well as the amount of nitrogen leached in the end of each growing seasons. In the second section of this chapter, we evaluated the role of legumes in enhancing the resiliency of maize and wheat to climate change under the studied crop sequences using SALTMED model and CMIP6 mean projection of two future scenarios, namely SSP1-2.6 and SSP5-8.5. Under future climate scenarios, the model simulated the losses in the yield and the season length of the studied crops, where the highest yield losses will be found under CS1 and the lowest yield losses will be found under CS3. Nitrogen use efficiency and water productivity values of the studied crops will be the lowest under CS1 and highest under CS3. The above results proved that the integration of legume crops in maize and wheat cropping system can increase its resiliency and mitigate the harmful effect of climate change, as well as reducing yield losses.