Individual study: Crop residue management and tillage methods for conserving soil and water in semi-arid regions
Unger P.W., Stewart B.a., Parr J.F. & Singh R.P. (1991) Crop residue management and tillage methods for conserving soil and water in semi-arid regions. Soil and Tillage Research, 20, 219-240
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Retain crop residues
A review of 76 papers in 1991 (Unger et al. 1991) described a study (Russel, 1939) that found no water runoff under straw residue no tillage (0 mm) and highest runoff under disc tillage with no straw (60 mm). Another study (Greb, 1979) found higher water storage (157 mm) and wheat Triticum aestivum yield (2.16 Mg/ha) under stubble mulch with minimum tillage than under conventional tillage with dust mulch (a loose dry layer of soil) (102 mm, 1.07 Mg/ha respectively). Papendick (et al. 1990) found that the soil loss ratio (comparing loss from covered to loss from bare soil) decreased with increasing soil cover by crop residues (ratio of 0.8 at 10% cover,0.2 at 35% cover and 0 at 65% cover).
Change tillage practices
A review of 76 papers in 1991 (Unger et al. 1991) reported lower runoff under no-till (9 mm), soil rotivated to 15 cm depth (24 mm), cultivated with no-till (57 mm), and ploughed then disk-harrowed (55 mm), compared to soil ploughed to 15 cm depth (171 mm) (Burwell et al.1966). Corn Zea mays yield increased with tillage depth, the effect greatest in soil with low water holding capacity (8 mm/m soil depth, Arora et al. 1991). The studies showed that contouring (cultivation across-slope rather than down-slope), furrow diking (small earthen dikes built at intervals between tillage ridges in semi-arid areas), strip-cropping (narrow strips of plants or plant residues), terraces (level terraces are built across a slope), and graded furrows (miniature graded terraces) can be used together with tillage to increase soil and water conservation benefits.