Site-specific nutrient management (SSNM)
focuses on developing a nutrient management
program that takes the following aspects into
account:
} Indigenous nutrient supply at each site
(‘site-specific’).
} Temporal variability in plant N status
occurring within one growing season
(‘season-specific’).
} Medium-term changes in soil P and K
supply based on the cumulative nutrient
balance.
Management of nitrogen
To optimize N use efficiency for each season,
a dynamic N management strategy is required,
in which the adjustment of the quantity of N
applied in relation to the variation in indigenous
N supply is as important as timing, placement,
and source of applied N. Nitrogen
management should therefore include the
following measures:
An estimate of crop N demand, potential
N supply from indigenous sources (soil,
biological N2 fixation) and N recovery
from inorganic and organic sources
applied. These factors are used to
estimate the total fertilizer N requirement.
An estimate of the need for a basal N
application according to soil N release
patterns, crop variety, and crop
establishment method.
Plant N status monitoring to optimize the
timing of split applications of mineral N
fertilizer in relation to crop demand and
soil N supply.
Long-term soil and crop management
practices to optimize the indigenous
nitrogen supply (INS).