NAIROBI， Sept. 6 (Xinhua) -- Agriculture experts on Tuesday cited declining soil fertility and rising prices as key challenges inhibiting high productivity in the agriculture sector in Africa.
Speaking at the ongoing Sixth African Green Revolution Forum in Nairobi， the experts noted that 28 percent of rural Africa's cultivated land is considered to be degrading over time， a cause of low food security and low economic growth.
Thomas Jayne， a professor in the Department of Agricultural， Food， and Resource Economics at Michigan State University claimed African farmers have used fertilizer for long and thus leading to diluting of key nutrients in the soil.
Experts observed that even though there has been progressive performance in the sector for the last 10 years， soil has lost strength to boost production.
David Ameyaw， head of Monitoring and Evaluation for Alliance for Green Revolution in Africa noted that land prices also appear to have risen dramatically in areas of high agro-ecological potential within reasonable proximity of urban areas.
"These trends have created new stresses on the ability of customary tenure systems to protect small-scale farmers land from encroachment. The region has experienced rising demand for agricultural land both from international and national companies as well as urban investor farmers，" Ameyaw said.
In Kenya land prices have increased by more than 100 percent in the last decades. This has led to sale of prime agricultural land in some of the counties near Nairobi.
Ameyaw said governments have also become increasingly aware of the potential for revenue generation from the lease of agricultural land and many are reportedly putting pressure on customary land administration institutions to gain leverage over unutilized rural land.
"This trend is particularly problematic given that land rights under most customary systems are almost by definition undocumented，" he added.