Managing Soil Heterogeneity in Smallholder African Landscapes Requires a New Form of Precision Agriculture.

TITTONELL, P. ; VAN DIS, R.; VANLAUWE, B.,; SHEPHERD, K.D.,

Soil Specific Farming. Precision Agriculture. Advances in soil science

CRC Taylor and Francis

Lugar: Boca Ratón FL; Año: 2016; p. 199 - 224

Tittonell, P., van Dis, R., Vanlauwe, B., Shepherd, K., 2016. Managing Soil Heterogeneity in Smallholder African Landscapes Requires a New Form of Precision Agriculture. In: Lal, R., Stewart, B.A. (eds.), Soil Specific Farming, Advances in Soil Science, CRC Press - Taylor & Francis Group NW, Boca Raton, FL pp. 199-224.Soil spatial heterogeneity is pronounced in African smallholder agricultural landscapes, resulting from the interaction between geological and geomorphological factors and the effects of land use and management over time. There are several ways of categorising such spatial soil heterogeneity or soil fertility ?gradients?. Across sub-Saharan Africa, four dominant patterns have been described: (i) continuous gradients, (ii) discrete gradients, (iii) discontinuous gradients and (iv) inverse gradients. The most common variable used to describe these patterns is the distance from the fields to the homesteads. The existence of soil variability, particularly the extent and distribution of degraded soils, affects the ability of soil improving techniques to restore crop productivity, notably the efficiency of capture and use of applied nutrients. Based on such differences, soils can be classified into three categories: non-responsive fertile soils, responsive soils and non-responsive poor soils. Farmers use local soil quality indicators to identify these categories of soils in the landscape, and allocate their productive resources ? including labour ? preferentially to fields perceived as fertile, reinforcing soil variability. New technologies for soil surveillance based on their spectral reflectance are available to map not only the extent and distribution of such soil categories but also their responsiveness to different interventions. Yet, to develop spatially explicit recommendations to address specific soil problems it is still necessary to combine high tech solutions with farmers? perceptions, knowledge and local indicators of soil fertility. A new form of precision agriculture for smallholder landscapes is much needed.