Swamp and dryland soils of the Okavango delta. Soil, water and crop production in Ngamiland

arid soils bilan hydrique du sol crops cultivos cultural methods feed crops fertilidad del suelo institution de recherche introduction de plantes irrigation par aspersion irrigation systems mode de culture pantano perennials plant introduction plantas forrajeras plantas perennes plante de culture production recherche research research institutions sistemas de riego soil fertility soil water balance sol de zone aride sprinkler irrigation swamps variedades varieties