Effect of spatial arrangement and nitrogen levels on yield of potatoes and beans grown as intercrops
Abstract
Two field experiments were conducted at the University of Nairobi's
Faculty of Agriculture farm (Field Station) to investigate the effect of
planting patterns (PP) and nitrogen (N)application on growth and yield of
intercropped potatoes and beans. Two varieties (V)of potatoes, the early
maturing variety Annette (VI) and the late maturing variety B53 (V2)were
intercropped with the early maturing Rosecocco (GLP-2) variety of beans
during the short rains of November - March 1993 and long rains of May -
August, 1994. The treatments used were four planting patterns, four
nitrogen levels and two potato varieties, tested in a factorial experiment
laid out in a completely randornised block design with three replicates.
The planting patterns consisted of sole crop of potatoes or beans (PPI),
potatoes and beans in alternate rows (PP2), potatoes and beans in
alternate hills within the row (PP3) and potatoes and beans in the same
hill (PP4).The nitrogen levels were Okg/ha (Nl), 37.5kg/ha (N2), 75kg/ha
(N3) and 112.5kg/ha (N4). During growth, plants were sampled for dry
matter, nodule number and nodule weight determination every fortnight
starting from four weeks after emergence. At maturity, yield and yield
components were determined for both beans and potatoes.
Results showed that potato dry matter yield in sole crop out yielded the
other planting patterns early in the season upto 6 weeks after emergence
and beyond this, those planted on the same hill with beans were
significantly higher than alternate hill and alternate row patterns. The
higher nitrogen levels of 75kg/ha and II2.5kg/ha gave sole crop dry
matter yields that were significantly higher than the intercrop patterns.
Bean dry matter yields of sole crop and alternate rows were statistically
similar at the lower nitrogen levels of 0 and 37.5kg/ha nitrogen but as the
nitrogen was increased to 75kg/ha and 112.5kg/ha the sole crop out
yielded all the intercropped intercropped planting patterns.
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At zero nitrogen level, intercropping in the same hill increased potato
tuber yields by 3.8% and 15.2% in Annette and B53, respectively,
compared to intercropping in alternate rows, in the first season. In the
second season same hill yields were higher than alternate row yields by
10.1%and 12.3% for Annette and B53 respectively. Potato yield advantage
arising from increased proximity between the intercrop species
disappeared at higher nitrogen levels of 75kg/ha and 112.5 kg/ha. Sole
beans yielded significantly more than beans in the intercropped
treatments. Bean yield responded positively to nitrogen fertilizer but
higher nitrogen levels depressed this parameter in some cases.
Intercropping had yield advantages over monocropping. Land equivalent
ratios increased with increasing intimacy between the intercrops
especiallyunder low nitrogen. The land equivalent ratio values for same
hill planting were significantly higher than for the other intercrop
patterns of alternate row and alternate hills at the low nitrogen levels of 0
and 37.5Kg/ha. The land equivalent ratio parameter declined with
increase in nitrogen fertilizer to 75 and 112.5kg/ha., with the same hill
intercropping exhibiting the highest decline at the highest nitrogen level.
In close analysis of the two potato varieties, the results indicated that
same hill yields of B53 benefited more from the close intimacy than the
Annette at low nitrogen levels. The results therefore, while underscoring
the benefits of intimacy in exploiting the complimentary effects of the
legumes, also indicates that the potato variety which stayed in the field
longer even after harvest of the beans, gained relatively more. This is
consistent with the idea that Nitrogen released from dead and decaying
roots and root nodules may continue to benefit an accompanying
intercrop.
Citation
Nyanga, R.A(1998).Effect of spatial arrangement and nitrogen levels on yield of potatoes and beans grown as intercropsSponsorhip
University of NairobiPublisher
Department of soil science, University of Nairobi
Description
Msc Thesis