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combination of tied ridges and fertilizer than with tied ridges and fertilizer alone
(Nagy et al. 1990 ). Likewise, the sorghum yield enhanced from 118 to 388 kg ha−^1
when the crop was planted on 1.5 m tied ridges, and to 1071 kg ha−^1 when 50 kg N
ha−^1 was applied to the tied-ridges (Nyakatawa 1996 ).
Mulching in dryland soil may be beneficial to improve the water conservation.
Mulching also modulates the soil temperature and soil moisture regimes, and thus
help improving the soil nutrient utilization (Lal 1974 ). In two independent studies,
higher utilization of N and P was reported with mulch in sorghum (Raghavulu and
Singh 1982 ), and barely (Hordeum vulgare L.; Agarwal and De 1979 ). Application
of N combined with mulching improved wheat yield after maize in dryland soil
(Prihar et al. 1981 ). van Duivenbooden et al. ( 1999 ) also reported that improvement
in soil water storage and its availability to crop plants at critical growth stages
increases the fertilizer use efficiency and the efficiencies of other farm inputs. In
India, Singah and Das ( 1995 ) reported higher yield of dryland sorghum in a deep
soil having more stored water with N input of 50 kg ha−^1 than a shallow soil where
the response was only up to 25 kg ha−^1. Mid-season rainfall on a sandy soil deter-
mined the N use efficiency and yield of millet (Bationo et al. 1989 ). When mid-
season rainfall was low, the millet yield was not affected with fertilizer N. However,
when mid-season rainfall was more than the average, the application of N enhanced
the grain yield of millet by 4–5 folds (Bationo et al. 1989 ). They also reported that
response of millet to applied N was low in dry years which was enhanced in the
years when rainfall was optimum. Application of N application at 30 kg N ha−^1
provided the fertilizer N use efficiency as high as 25 kg grain kg−^1 N (Bationo et al.
1989 ).
In China, two types of mulches haven been used widely in dryland agriculture,
viz. straw mulch and plastic mulch. Use of plastic mulch conserve soil moisture,
enhances the soil temperature, and availability of N by reducing the losses of N
through volatilization, thus enhancing the N use efficiency and crop yield. In Gansu
province in China, use of plastic mulch enhanced the yield of wheat by 1500 kg
ha−^1. However, the environmental risks associated with the plastic mulch is the slow
rate of decomposition, and eventually the mulch becomes a pollutant. The benefits
of straw mulching are the same (e.g., water conservation and increase in nutrient use
efficiency) as the plastic mulch, but straw mulch lowers the soil temperature and
delays the germination of spring sown crops. When combined with conservation
tillage, the benefits of straw mulching to conserve soil water in dryland area may
increase several folds. Plastic mulch causes rapid decomposition of soil organic
matter, while straw mulch lowers the soil organic matter decomposition due to low
temperature.
Beside the total seasonal rainfall, the distribution of rainfall during the crop
ontogeny also triggers the fertilizer N use efficiency. For example, in Canada, the
rainfall during grain filling and at seeding was the most beneficial than at other
growth stages (Campbell et al. 1988 ). The amount/distribution of rainfall in north-
ern India during the vegetative and reproductive stages has been identified as a
decisive factor to determine the fertilizer N use efficiency (Sandhu et al. 1992 ). The
pattern of rainfall in dryland areas can also affect the effectiveness of fertilization
A. Nawaz and M. Farooq