Grain Legumes and Green Manures for Soil Fertility in ... - cimmyt

A SOCIO-ECONOMIC ANALYSIS OF LEGUME· PRODUCTION MOTIVES
AND PRODUCTIVITY VARIATIONS AMONG SM.ALLHOLDER FARMERS
OF SHURUGWI COMMUNAL AREA, ZIMBABWE
CHARLES NHEMACHENA1, HERBERT K MURWIRA2, KILIAN MUTIR0 2
and PAULINE CHIVENGE 2
1Department of Agricultural Economics and Ext£!nsion,
University of Zimbabwe, Box MP167, Mt Pleasant,
2 Tropical Soil Biology and Fertility Institute of CIA T, Department of Soil Science and
Agricultural Engineering, University of Zimbabwe, Box MP228,
Mt Pleasant, Harare, Zimbabwe
Abstract'
The impacts of poor soil fertility in Zimbabwe's communal farming systems have great implications on the food security
and livelihoods of communal households. This study identifies opportunities for using legumes in replenishing soil
fertility to improve agricultural production in the communal sedor through an assessment of social and economic
factors that affect legume production. The study also identifies the economic potential of green manures on farm.
Interviews with individual farmers and focus group discussions were conducted to establish perceived roles for legumes
in soil fertility improvement. Data were also collected from the on farm trials. Analytical tools such as frequency
analysis, regression analysis, descriptive analysis and cost benefit analysis were used to test proposed hypotheses.
The motives for legume production were indicated to be food, cash and sometimes soil fertility improvement. It was also
shown that the area under legume production, legume crop prices and labour availability are important factors affecting
legume productivity. Legume production as indicated by the area cropped, yield, income and home consumption is very
low. The constraints raised by farmers of limited cropping area, lack of markets, seed unavailability and lack of sufficient
labour greatly contribute to the low status of legumes in the smallholder cropping system. The potential exists to
intensify the use of legumes in the communal areas. The approach required to do this needs to be holistic and take into
account their multiple use purposes, input and output markets, and promote new legumes.
Key words: socio-economics, grain legume, motives for legume production, soil fertility
Introduction
Diminishing soil fertility remains the most limiting
biophysical constraint to smallholder agricultural
production in Zimbabwe. Increasing scarcity of
locally derived nutrient sources and the changing
socio-economic environment has rendered soil
fertility improvement in smallholder farming
systems in semi-arid and sub-humid Africa more
difficult and complicated. External options for
improving soil fertility have failed over the years
because of inconsistency with the current
circumstances of the farmers.
The major sources of N available to farmers include
animal manure, mineral fertilizers, woodland leaf
litter and termitarium soil. Cattle manure, which is
the commonly used source of organic fertilizer, is
often limited in its supply by lack of cattle among
farmers. Where available it is often of low quality
due to the poor state of the rangelands and lack of
adequate proteins in the animals' diet. Use of
mineral fertilizers, especially ammonium nitrate
(34.5% N), which is the major alternative source of
N, is limited in the communal sector due to high
costs, unavailability, risk and low returns to
investment due to poor crop prices. Furthermore,
the traditional sources of N, which include
woodland leaf litter, have been depleted due to
rapid population increases. There is an opportunity
for nitrogen-fixing legumes to be used as cheap
alternative sources of soil fertility improvement to
help reverse the worsening poverty in these farming
systems.
Though traditional legume crops such as groundnut
are widely grown in the smallholder farming
system, areas planted and yields are very low. Thus,
there is need for intensive promotion of these crops
for them to be significant sources of N to enhance
agricultural production. This study explores the
motivation behind legume production among
smallholder farmers, the important factors affecting
legume productivity and the economic potential of
Grain Legumes and Green Manures for Soil Fertility in Southern Africa 223