The Eleventh Regional Wheat Workshop For Eastern ... - Cimmyt

EFFECTS OF CROP ROTATION, TILLAGE METHOD AND N APPLICATION
ON WHEAT YIELD AT HANANG WHEAT FARMS, TANZANIA
P.L. Antapa 1 and W.L. Mariki 2
l HWC-CMSC, P.O. Box 96, Katesh, Tanzania
2SARI, P.O. Box 6024, Arusha, Tanzania
ABSTRACT
Crop management options which optimize tillage, residue management and
herbicide practices are likely to provide more sustainable and efficient farming
systems, especially in relatively marginal environments like those prevailing at
the Hanang Wheat (HWC) farms. A crop rotation trial was established at the
HWC from 1994/95-1999/2000 to determine whether wheat yields at the
HWC farms could be improved through crop rotation with soybean and pigeon
pea; rotations were compared in factorial combination with tillage practice and
N application. Across four years of experimentation, rotations of wheat with
soybean or wheat with pigeon pea, both under minimum tillage, resulted in the
highest wheat yields, 2.82 and 2.80 t/ha, respectively. Soybean-wheat or
pigeon pea-wheat rotations are recommended for improved and sustainable
wheat yields at the HWC farms. However, further research is needed to
determine optimal rotation frequencies. Use of N fertilizer alone is not
recommended to increase wheat production at the HWC farms. However, N
application of 30 kglha is recommended in conjunction with minimum tillage
to increase wheat production at the HWC farms.
INTRODUCTION
Crop management options which optimize tillage, residue management and herbicide
practices are likely to provide more sustainable and efficient farming systems especially in
marginal environments like the Hanang wheat farms in northern Tanzania.
In areas where soil moisture limits plant growth, zero till (ZT) systems have been reported to
produce crop yields similar to (Carter and Rennie, 1985) or higher than (Tessier et al., 1990)
conventional tillage (CT). However, in relatively humid environmental conditions, crop yield
for ZT systems were comparable to (Carter et al., 1988) or lower than (Parsons and Koehler,
1984) those obtained under CT systems. Crop response to ZT was found to be inversely
proportional to the risk of compacting the soils (Rydberg, 1992). It has been found that the
grain yield potential ofCT practices is generally site specific (van Doren et al., 1976).
Adapting crop rotation at the Hanang wheat farms can be a long-term and sustainable
solution to the existing weed, soil fertility and plant disease problems which currently prevail.
Alternate crops could also help in spreading the risk involved in the mono-cropping system
which is the conventional practice at the HWC. Through research programs carried out at
HWC farms, some crops which perform very well have already been identified that could be
grown in rotation with wheat. These include: soybeans, sunflower, safflower, common beans,
maize and flax. However, availability of a market for these various crops has been the major
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