Agriculture, Ecosystems and Environment 79 2000 61–72
Nitrogen balances for households in the mid-hills of Nepal
C.J. Pilbeam
a,∗
, B.P. Tripathi
b
, D.P. Sherchan
c
, P.J. Gregory
a
, J. Gaunt
d
a
Department of Soil Science, The University of Reading, Whiteknights, P.O. Box 233, Reading, RG6 6DW, UK
b
ARS-Lumle, P.O. Box 1, Pokhara, Nepal
c
Formerly ARS-Pakhribas, Dhankuta, Nepal
d
IACR-Rothamsted, Harpenden, Herts, AL5 2JQ, UK Received 24 February 1999; received in revised form 24 September 1999; accepted 27 October 1999
Abstract
Sustainable production requires balanced resource use and it is the management decisions at a household level that determine nutrient fluxes and the economic viability of enterprises. Traditionally, the agricultural systems of 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 sources to determine a N balance for a hypothetical household
and to assess the sustainability of current farming systems with respect to N. For a hypothetical 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 currently in
balance with inputs across the boundary of about 26 kg N a
− 1
mainly in fertilizer and losses, excluding gases, of about 60 kg N a
− 1
mainly in crop removal. Tree fodder and grasses are a major source of N 80 kg N a
− 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 to
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 losses via leaching and gases are
largely unquantified. It is concluded that the 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 land to agricultural land. The magnitude of this movement
is not known, because the quantities of vegetation gathered from inside and outside the household boundaries are not known. © 2000 Elsevier Science B.V. All rights reserved.
Keywords: Farming systems; N budget; Nepal
1. Introduction
The middle hills of Nepal, lying between 1000 and 1600 m, cover 4.44 million ha Carson, 1992 of which
approximately one quarter is cropped 1.23 million ha; LRMP, 1986a. Nationally, 70 of the cropped
area is as rain-fed terraces bari land, while irrigated
∗
Corresponding author. Tel.: +44-118-9316557; fax: +44-118-9316660.
E-mail address: c.j.pilbeamreading.ac.uk C.J. Pilbeam
land khet constitutes the remainder LRMP, 1986a. There is little deviation from this distribution within
the five development regions in Nepal. In 1991, more than 50 of the population of Nepal, which was then
18.5 million, lived in the hill and mountain areas CBS, 1991, with an average density of 89 people km
− 2
. Agricultural productivity of the middle hills is, there-
fore, of vital interest to many Nepalese. Traditionally, crop production, livestock husbandry
and forestry are integrated closely in the agricultural systems of the mid-hills Carson, 1992; Kiff et al.,
0167-880900 – see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 - 8 8 0 9 9 9 0 0 1 4 3 - 7
62 C.J. Pilbeam et al. Agriculture, Ecosystems and Environment 79 2000 61–72
1995. The grazing of animals in the forest, the col- lection of forage from the forest to feed housed ani-
mals, and the use of forest litter for animal bedding, mean that there is a net movement of nutrients from
the forest to the cropped areas via livestock produc- tion Turton et al., 1995. In addition to the use of ma-
nures and composts, soil fertility of the cropped areas is maintained by a variety of other techniques, for ex-
ample diverting nutrient-rich flood waters on to khet land, tethering animals on cropped land, and growing
legumes either as green manures or in rotation. Crop yields in the traditional systems are low and insuffi-
cient to support a burgeoning population. Intensifying agricultural production increases productivity, which
is necessary, but simultaneously results in more open nutrient cycles Jodha, 1990 thereby increasing the
susceptibility of the system to larger nutrient losses and, perhaps, reducing its long-term sustainability.
A nutrient balance quantifies the input of a particu- lar nutrient to an area of land and subtracts from this
the output of the same nutrient from the same area of land Stoorvogel et al., 1993. The balance may
be positive, if inputs exceed outputs, or negative, if outputs exceed inputs, and is a quantifiable indicator
of sustainability Smaling et al., 1996. Nutrient bal- ances not only indicate sustainability but, by chang-
ing the inputs and outputs, also allow the outcome of different future scenarios to be compared Stoorvo-
gel et al., 1993. While these scenarios are generally compared on the basis of the particular nutrient, their
socio-economic impact can also be evaluated if rele- vant economic data are available de Jager and Smal-
ing, 1997. Nutrient balances can be constructed at a range of scales, for example supra-national Stoorvo-
gel et al., 1993 or district Smaling et al., 1993 but it is at the household level that nutrient fluxes are most
directly affected by management decisions Smaling et al., 1996. Furthermore, the concept of sustainabil-
ity combines balanced resource use with economic vi- ability, and it is at the level of the household that the
biological, social and economic considerations are in- tegrated.
This paper aims to determine a N balance for a hypothetical household in the mid-hills of Nepal and
thereby highlight gaps in the quantitative knowledge of N flow. Using the quantitative cycle, sustainability
was assessed with respect to N of the current farming systems in the hills of Nepal, along with the impact of
perturbations to the system caused by either a change in the supply of N to or from parts of the system, or
an increase in the efficiency of N use Pandey, 1996.
2. Defining a typical household in the mid-hills
