Sustainable production requires balanced resource use and it is the managem
ent decisions at a household level that determine nutrient fluxes and the e
conomic viability of enterprises. Traditionally, the agricultural systems o
f the mid-hills of Nepal have relied on the close integration of forestry,
livestock husbandry and crop production but increasing population and other
social changes are straining these systems. This paper uses diverse source
s to determine a N balance for a hypothetical household and to assess the s
ustainability of current farming systems with respect to N. For a hypotheti
cal household holding 1 ha of land with two-thirds of it rainfed hillside (
bari-land) and one-third irrigated lowland (khet-land), the system is curre
ntly in balance with inputs across the boundary of about 26 kg Na-1 (mainly
in fertilizer) and losses, excluding gases, of about 60 kg Na-1 (mainly in
crop removal). Tree fodder and grasses are a major source of N (80 kg Na-1
) to the household. A major pathway for the flow of N within the system is
via the forage fed to livestock, and the subsequent application of manure t
o crops. Typically, manure and compost supply 100 kg N to crops (four times
that supplied by fertilizer) and produce crops with a N content in grains
of 36 kg N. The N losses via soil erosion are shown to be small but the los
ses via leaching and gases are largely unquantified. It is concluded that t
he use of tree fodder and forage from forest areas and grasses from terrace
risers as animal feed ensures a net movement of N from non-agricultural la
nd to agricultural land. The magnitude of this movement is not known, becau
se the quantities of Vegetation gathered from inside and outside the househ
old boundaries are not known. (C) 2000 Elsevier Science B.V. All rights res
erved.