Summary: Breeding Plants for Problem Soils — Current Knowledge and Prospects

Abstract

The chapters in this book have been concerned with a range of different soil problems that limit plant productivity and with the strategies that might be applied to produce sustainable increases in productivity on these soils. Problem soils can generally be divided into two classes according to whether toxicity or deficiency predominate (although toxic soils are often deficient as well). Of naturally occurring problems, the toxicity of aluminium, iron and manganese are the most widespread (Chap. 7). These are common elements whose availability to plants is associated with acid soils. Factors which lead to soil acidification, such as acid rain and excessive fertilisation, increase the incidence of toxicities by these metals. Many soils are naturally saline, but salinisation caused by irrigation is, and has been historically, one of the most worrying cases of the lack of sustainability of agriculture. On some estimates, up to half of irrigation systems are affected by salination. In contrast, heavy metal toxicity usually affects only small and localised areas such as the vicinity of mines. If saline soils have received the most attention in the book it is because of the interests of many of the authors. Soil toxicities are generally difficult to alleviate by management practices.