129the fertilizer use efficiency by 8–16 % relative to the application of fertilizer without
crop residues (Hegde 1980 ).
Another pragmatic way to add the organic matter into the dryland soil is the
growing of leguminous crops in situ, and then ploughing as green manure. Indeed,
the green manures are primarily used as soil amendment to provide the soil with
nutrients for upcoming crops, and are recognized as the most secure and clean
source of organic fertilizer in conventional agriculture in China (Cao and Huang
2009 ), and other parts of world. Use of legume crops as green manures help enhanc-
ing the grain yield of the proceeding cereal crops by adding N, maintaining biologi-
cal activity and soil fertility and decreasing the use of synthetic fertilizers (Evans
et al. 2003 ; Walley et al. 2007 ; Espinoza et al. 2012 ; Seymour et al. 2012 ; Yu et al.
2013 ; Hayden et al. 2014 ). For instance, Hegde ( 1980 ) proposed the incorporation
of cowpea as green manure to enhance the yield and fertilizer use efficiency of rainy
season castor and sorghum on a coarse textured Alfisol of Hyderabad, India. In
China, growing leguminous green manure crop prior to wheat improved the yield
and water use efficiency of wheat by 13 and 28 %, respectively, and was very useful
to maintain the soil water balance than fallow-wheat crop rotation (Zhang et al.
2016 ). In another study, green manuring with lentil (Lens culinaris L.) maintained
the wheat productivity and offset the needs of N fertilizer after three cropping cycles
than the conventional-wheat–fallow rotations (Allen et al. 2010 ).
The timing of manure application to the dryland soil is very important. In a
4-year study, application of farm yard manure prior to onset of moonsoon and appli-
cation of mineral fertilizers about 2-month before sowing was the most beneficial
(Singh et al. 1985 ). Studies in dryland regions of Kenya showed that the goat manure
has superior soil fertility impact than chemical fertilizer (e.g., diammonium phos-
phate) (Onim et al. 1990 ), and it may be preferred in dryland crop production. In
dryland regions, growing of multipurpose tress within crops may help to provide
nutrient pool by capturing nutrients from the atmosphere and fixing them through
biological nitrogen fixation, and extracting nutrients from deep soil horizons and
their deposition in the soil through leaves and other plants parts after decomposition
(Sanchez et al. 1997 ). However, they opined that in low rainfall regions, tree planta-
tion within crops may negatively impact the crop growth by using the available soil
moisture (Sanchez et al. 1997 ).
3.5 Water Conservation
Effective water management in drylands may enhance the availability and transfor-
mation of nutrients from fertilizers or from the soil. The organic N mineralization is
proportional to the amount of water present in the soil, and the net mineralized
nitrate-N is enhanced with increase in soil water contents under an optimal tempera-
ture range (Li et al. 2009b). Thus, the benefits of fertilizer application to the dryland
crops can be enhanced through effective water conservation in dryland areas. In
Burkina Faso, the grain yield of sorghum was highest at on-farm locations with the
Nutrient Management in Dryland Agriculture Systems