By how much is the maize production in Southern Africa predicted to decreade by 2030 ?
In the long run , the climatic change could affect agriculture in several ways : " productivity " , in terms of quantity and quality of crops " agricultural practices " , through changes of water use ( irrigation ) and agricultural inputs such as herbicides , insecticides and fertilizers " environmental effects " , in particular in relation of frequency and intensity of soil drainage ( leading to nitrogen leaching ) , soil erosion , reduction of crop diversity " rural space " , through the loss and gain of cultivated lands , land speculation , land renunciation , and hydraulic amenities .