Enhancing crop yields in the developing countries through restoration of the soil organic carbon pool in agricultural lands

Abstract

Food production in developing countries, estimated at 1223 million metric tons (Mg), must be increased by 778 million Mg or 2Á5 per cent y À1 between 2000 and 2025 to meet the needs of an increased population and projected change in diet. Among numerous options, the one based on enhancing soil quality and agronomic productivity per unit area through improvement in soil organic carbon pool has numerous ancillary benefits. The available data show that crop yields can be increased by 20-70 kg ha À1 for wheat, 10-50 kg ha À1 for rice, and 30-300 kg ha À1 for maize with every 1 Mg ha À1 increase in soil organic carbon pool in the root zone. Adoption of recommended management practices on agricultural lands and degraded soils would enhance soil quality including the available water holding capacity, cation exchange capacity, soil aggregation, and susceptibility to crusting and erosion. Increase in soil organic carbon pool by 1 Mg ha À1 y À1 can increase food grain production by 32 million Mg y À1 in developing countries. While advancing food security, this strategy would also off-set fossil fuel emissions at the rate of 0Á5 Pg C y À1 through carbons sequestration in agricultural soils of developing countries.

Carbon management in dryland agricultural systems. A review

“…However, in these areas, conventional management techniques hinder the presence of an adequate protection of the soil surface: (i) the use of intensive tillage in herbaceous and tree crops (Álvaro-Fuentes et al 2008), (ii) feed needs for animal production (López et al 2003), (iii) excessive grazing (Hoffmann et al 2008), and (iv) the recent high feedstock demand for bioenergy (Miner et al 2013). In developing countries of Asia and Africa, the extractive nature of using crop residues as fodder for cattle and animal dung as a cooking fuel poses a serious problem to soil quality and the sustainability of crop production (Lal 2006). In those countries, soil organic carbon decline needs to be counteracted by increasing the amount of crop residues produced.…”

Reversibility of Soil Productivity Decline with Organic Matter of Differing Quality Along a Degradation Gradient

“…The anthropogenic perturbations, which accompany this land-use change through continuous cultivation and land tillage cause an immediate and rapid loss of carbon (Davidson and Ackerman 1993;Tilman and others 2002;McLauchlan 2006;Solomon and others 2007) due to the disruption of the physical, biochemical, and chemical mechanisms of soil organic matter (SOM) stabilization exposing it to microbial degradation. In resource-limited agricultural regions, this dynamic is accompanied by a removal of crop residues for feed and fuel as well as a shortage of agricultural inputs and hence lower plant growth, leading to reduced-carbon returns by residues to soil (Lal 2006).…”

“…Soil organic matter decline leads to reduced cation exchange capacity (CEC) resulting in weakening of nutrient retention and supply capacity as well as water retention capacity of the soil (Lal 2006). Hence, efforts to replenish soil fertility through the application of plant nutrients in readily available forms (mainly through the use of mineral fertilizers) is offset by almost immediate leaching of the mobile nutrients into the subsoil rendering them unavailable to most crops (Hö lscher and others 1997; Giardina and others 2000;Renck and Lehmann 2004).…”

“…This poses a great challenge to crop productivity, especially in soils with low-activity clays, such as the highly weathered and leached soils of the humid tropics (Sanchez 1976;Jones and others 1997;Steiner and others 2007) and as a consequence yields typically decline dramatically with losses in SOM (Lal 2006). Although enhanced use of mineral fertilizers could be viewed as a solution, this approach is often inefficient due to the limited ability of low-activity clay soils to retain nutrients due to low SOM contents (Lal 2006). Restoring and maintaining SOM content is thus essential to long-term crop productivity.…”

“…In contrast, sandier soils typically have lower CEC and water holding capacity as well as SOM than finer textured soils. Additions of organic matter provide all of these benefits and may thus improve sandier soils to a greater extent (Lal 2006). Therefore, it is not clear whether productivity will be enhanced to a greater extent in finer or coarser textured soils by organic matter additions of contrasting quality.…”