ADB_book_18 April.qxp - Himalayan Document Centre - icimod

Clearing forests for cultivation to meet the foodrequirements of the growing population, particularlyover the sloping areas of the middle Hills, hasresulted in accelerated soil erosion, decliningproductivity, and sedimentation in downstreamareas and the Terai plains (Zimsky 1999). Forestresources have also been pressured by increasingnumbers of livestock, from 14.9 million head(equivalent to 9,790 thousand livestock units (LU) in1984 to 17.6 million head (11,226 thousand LU) in1998. The increasing livestock population hasincreased the demand for fodder and leaf litter fromthe forest, causing land erosion especially in the midHill region.Land degradation due to desertification hasbeen seen over about 10,000 ha of dry and cold landin the western Himalayan districts such as Dolpa andMustang. This is mainly due to scanty vegetation onmarginal land grazed by an excessive number oflivestock.Agricultural land is subject to ever-greaterintensification of use through double and multiplecropping to produce more food for the increasingpopulation. Soil micronutrients are depleting due tooveruse, inadequate supplements, and imbalancedapplication of fertilizers. For instance, the most recentdata available (DOA 2000) show low or mediumnitrogen content in 48% and 40% of of 9,827 farmlandsamples analyzed; 64% of 7,520 farmland samples hadlow organic matter and high to medium potassiumcontent and 35% had low phosphorous content andoverall deficiency in micronutrients such as zinc,manganese, molybdenum, copper, iron, and boron.These results indicate the highly nutrientdeficient status of farmland. As a result, productivityof crops has declined. The impact appears to bemuch more serious among poor farmers who mostlycultivate marginal lands on steeper slopes. The yieldsof maize and millet declined by more than 4% perannum between 1977 and 1997, while those of paddyand wheat increased by 16–37% per annum, duemainly to increased use of agro-chemicals (MOA1999). The use of high yielding seeds has increasedthe yield of crops per unit of land, but has resulted inless production of crop residues and greater uptakeof soil nutrients. This has forced farmers to dependmore on fertilizers than on manure, as well as to usedifferent types of insecticides and pesticides.Consumption of fertilizers (nitrogen, phosphate, andpotassium) increased from 7 kg/ha per year in 1980to 25 kg/ha per year in 1993.Average use of fertilizer by district ranges fromless than 10 kg/ha to more than 100 kg/ha. Thefertilizer use by Nepalese farmers is lowest amongthe South Asian countries. The use of pesticides is onthe increase. In 1998, the most recent year for whichreliable data are available, about 250 types ofpesticide, 40 types of herbicide, and various differentfungicides were used to minimize the loss ofagricultural production to pests and insects (MOF1999). However, despite the use of pesticides, cropyields have not increased significantly even thoughthe land ecology has been degraded. In commercialfarming, the national average consumption rate ofpesticides was estimated at 650 g/ha. In 1997, thePesticides Registration Office at the Department ofAgriculture estimated that about 60 tons of differentpesticides were imported into Nepal.Land ownership patterns are another cause ofland degradation. The agricultural statistics (CBS2004) indicate that the marginalized and smallfarmers with landholdings below one hectareaccount for 69% of all farmers, but these farms coveronly 31% of the total landholding area. As describedearlier, there has been an increase in the number offarmland holdings, while the average holding sizehas decreased.The land system in and around major urbanareas is affected by solid waste disposal. Productionof municipal waste increased from 0.144 million tonsin 1984 to 0.330 million tons in 1997 (CBS 1998; morerecent statistics are not available). Production oftoxic and hazardous waste increased from 270 to 512tons over the same time interval (Tuladhar 1999).This waste is disposed on land surrounding towns orin water bodies without any treatment.Land degradation is often seen as a side-effectof development work such as construction of roadsand irrigation canals along hill slopes, which havecontributed to landslides and land erosion. Laban(1979) estimated that 5% of all landslides in Nepalare associated with roads and trails. Theconstruction of roads is on the rise, and after roadsare built they are usually ravaged by recurrentlandslides and rock falls during the monsoon season.Stone quarrying can also lead to landslides andsoil erosion; however, no hard data are available.Impacts of Land DegradationOne of the direct impacts of land degradation is theloss of topsoil, which together with organic matterand plant nutrients influences soil fertility. Loss of soilat the rate of 5 tons/ha is equivalent to a loss of 75kg/ha of organic matter, 3.8 kg/ha of nitrogen, 10kg/ha of potassium, and 5 kg/ha of phosphorous inthe middle hills of Nepal (Carson 1992). Thecountry’s major rivers carry away thousands of tonsof sediment annually, but a large part of this occursnaturally and a significant part is composed ofriverbed load, embankment erosion, and similarcomponents.Chapter 3: Land Resources and Land Degradation35