Rainfed rice - IRRI books - International Rice Research Institute

Balanced Fertilisation for
Improving Soil Fertility and
Increasing Yield
Balanced fertilisation
C
rops need varying quantities of nutrients for their proper growth and
productivity. The variation occurs within crops based on the total
biomass production. These nutrients may be from either natural or
artificial sources. Since rainfed farming depends on rainfall at different
growth stages, there is always a factor of risk in such a type of farming.
Farmers do not want to spend scarce
resources on fertilisers and generally
apply only nitrogenous fertilisers.
However, the application of
phosphorus and potassium provides
drought resistance to the plants.
The first important rule of thumb
of input-responsive agronomy is
balanced nutrition based on a soil
test.
Balanced nutrition enhances
better root development.
Better root development enhances
the exploitation of water and
nutrients from deeper soil depths.
Application of phosphorus (P 2 O 5 )
and organic manure increases the
grain yield of upland rice, for
example, by about 50% in the case of
P 2 O 5 and double in the case of
manure. The results shown in the
graph below are based on a nitrogen
dose of 120 kg/ha, while the doses
of phosphorus (P 2 O 5 ) for this trial
were 0, 25 and 50 kg/ha.
General overview
Overexploitation and pressure on soil and
water, along with imbalanced fertiliser use,
deplete native nutrient reserves.
According to a national study, it is
estimated that about 10 m tons more of
nitrogen, potassium and phosphorus are
removed by crops in addition to the external
supply.
The rainfed farming system involves a high
risk factor, resulting in extensive
overexploitation of soil nutrients.
To increase productivity under rainfed
conditions, balanced fertilisation, along
with use of organic manure, is a must.
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