Fate of basal N and growth of crops cultivated under cassava-based intercropping
system@with reference to K application rate
Wayan Sabe Ardjasa, Tomonori Abe, Ho Ando, Ken-ichi Kakuda and Makoto Kimura
Soil Sci. Plant Nutrition 48-3, 365-370 (2002)
Cassava is the fourth most important staple food crop in Asia and main crop
in the cropping systems used in upland areas. Among staple crops, cassava
most abundantly absorbs potassium (K), suggesting that a nutrient disorder
might occur among the intercrops. A nutrient disorder in intercrops may affect
the fate of applied nitrogen (N) through the growth of intercrops. Strong
K-absorption ability of cassava can be potentially antagonistic to other
crops. If so, when the soil K level is critical in an intercropping system,
K application may result in increased yield through mitigation of the K antagonism
among intercrops, accompanied with nutrition improvement of other nutrients.
We conducted a field experiment to evaluate the growth of crops and the fate
of N fertilizer with reference to the application rate of K in a cassava-based
cropping system in South Sumatra. The results obtained were as follows;
1) The dry weight values and yield of cassava, upland rice and corn without
K application were lower than those with K application treatment. However,
no significant differences in the dry weight and yield of these crops were
observed between K application treatments of standard and double dose.
2) The recovery rate of basal N by upland rice and cassava was positively
related to the yield of each crop. Amount of immobilized N in soil applied
to upland rice was not affected by the application rate of K.
3) Total recovery rate of basal N applied to upland rice was 2 times higher
in the K application treatment than without K application treatment. It appears
that K application alleviated the N pollution problem by inducing a high
uptake rate of N fertilizer by crops.
Key Words: N dynamics, Southeast Asia, Ultisol, upland crop
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