Thesis Abstract of AGS Students

Phu Van Hoang (1993)

The problems of soil degradation and soil erosion due to deforestation has led to low agricultural productivity and poor living condition of people in the rural areas of the Northern-mountainous region of Viet Nam. The present study aims to evaluate productivity and the efficiency of soil conservation of some cropping systems under alley and non-alley systems.

A field survey with semi-structured interview was carried out in three villages, one of each belongs to Bac Thai, Cao Bang and Lang Son province during March to May, 1992 to study current land use practices and problems, and to understand farmers' opinions on conservation farming. The result of village survey was also used as a guide line for formulation of field experiments on the University farm

The results of field survey revealed that agriculture was driven toward self-sufficiency. Farmers focused more on lowland rice to upland farming. Prevailing cultivation on upland area was monoculture with simple traditional practices. Very few of farmers applied measure of soil conservation which lead to decreasing of crop yield.

The field experiment consisted of eight treatments having alley cropping (with and without hedgerows) as main plot and four cropping patterns (peanut-corn sequential cropping, peanut-upland rice relay cropping, peanut-cassava intercropping, and peanut-corn relay cropping) as subplot, in split-plot design with three replications.

The results indicated that hedgerows of Tephrosia candida contributed significantly in canopy cover in cropping system as well as provided crop residue which prevented soil movement by 11.64 ton/ha/year. There was also evidence of soil nutrient improvement under hedgerow inter-cropping after one cropping cycle.

For cropping systems, peanut-cassava intercropping produced the highest biomass, food yield, marginal gross, return to material cost, and return to labor cost. In terms of soil conservation, it also provided the higher canopy cover during peak of rainfall, and lower soil loss than others. Combination of suitable cropping systems such as peanut-cassava intercropping and alley cropping are potential practice to increase crop yield and minimized soil loss due to erosion.

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