Soil resources in upper Basho Valley.

Soil resources in upper Basho Valley. Åge A. Nyborg, 2007 Norwegian Forest and Landscape Institute. Soil management challenges in Upper Basho Valley Low nutrient content, low organic matter content, deficient soil moisture content, steep slopes and high rock content are some of the factors the people of Upper Basho Valley face in order to make a living of their land. The flat floodplains are easily accessible, but have poor soil quality due to low nutrient levels and wetness. Some of the better pasture areas are very steep and rocky, and access is often difficult and dangerous. The most fertile soils, the Cambisols and Luvisols, are moisture deficient large parts of the growing seasons. New irrigation channels will bring water to some of these areas, but the challenge is how to irrigate these steep slopes with highly erodible soils without washing the soil away. New irrigation channel at Bondopiri pasture Severe soil erosion The agricultural soils suffer from low fertilizer inputs. The quantity and quality of farmyard manure is not sufficient to cover the fertilizer needs, and chemical fertilizers are too expensive for most households. The village also lacks an efficient irrigation water management system. Too much irrigation water without a proper drainage system may lead to waterlogging and reduced soil quality. Excess use of irrigation water may also lead to nutrient loss through leaching. How can these problems be solved? Irrigated crops on steep slopes is a common sight in the mountainous parts of Asia. The crops are grown on man-made terraces and irrigation water is supplied through a network of channels. Some of the abandoned terraces in Basho are located below the new irrigation channel and just a short distance from Sultanabad village. These small terraces could be put into use again, perhaps with fodder production in combination with farm forestry. Fast growing tree species could utilize the excess irrigation water and at the same time reduce the exposure from the sun. A continuous plant cover and proper irrigation practices will reduce the risk of soil erosion. 1

The soils that are developed in loess are also susceptible to compaction when the soil is moist. Traffic from grazing animals may lead to deterioration of topsoil structure and compaction (link to trampling). A compacted topsoil restricts root development and accelerates water runoff and soil erosion. It is therefore important to keep grazing animals out of the irrigated Cambisol and Luvisol areas. The fertility status of the agricultural soils in the village may be improved by leaving some crop residue after harvest or by using other kinds of green manure. Today some farmers even collect the crop roots for animal fodder. Crop rotation systems may also be beneficial for the soil properties. But one of the most important measures for maintaining a better soil quality is the introduction of a better and more effective irrigation management system. New crop types and new varieties of existing crops that are adapted to the climate could be tried to improve crop yields, however the farmers must be able to follow up the crop s requirements including fertilizers, soil moisture, pest control etc. These measures cannot be introduced without proper training of the farmers. Soil is one of the most important natural resources, even in the remote high altitude valleys of Baltistan. To make a living from the land is a big challenge for poor farmers, and the challenge is even bigger without good knowledge about their soils and how to manage this resource in a sustainable way. Soil types in Basho valley The soil distribution in Basho Valley is highly correlated with the distribution of the different geological deposits such as glacial material, colluvial material, river and lake sediments and windblown loess. Glacial material is found as basal till or glacio-fluvial terraces on the valley slopes, or as moraines on the valley floor. The oldest surfaces are covered with loess, which is windblown silt originating from areas newly exposed by the retreating glacier. In post-glacial times, the valley has been reshaped by eroding rivers and streams, and by rockslides and avalanches. Today s valley sides are dominated by remnants of glacio-fluvial terraces and loess covered glacial till, together with scree fans and other colluvial deposits. Loess covered glacial material is mainly found on the lower valley slopes where they are dissected by stream gullies, scree corridors and fans. Remnants of glacio-fluvial terraces are found at different levels on the valley slope. The valley floor is dominated by rocky streambeds, or by silty and sandy floodplains where the end moraines across the valley have made natural dams. Ranga pasture on Basho river floodplain Rocky streambed of Basho river 2

Eight different soil types were described, sampled and mapped during the field visits in 1998, -99 and 2001. These soils have different parent material and represent different soil qualities. A description of the soils, their use and potentials follows. The soils are named according to WRB (World Reference Base of Soil Resources, 2006). (fig.1: Soil map. http://www.umb.no/?viewid=22264) Gleyic Fluvisols Most Fluvisols are developed in river sediments. Their main feature are layers with varying texture and organic matter content. They are commonly found on river floodplains where they may be inundated by river water during periods of flood. In the study area we find Gleyic Fluvisols on level floodplains along the valley floor. The largest floodplain is Ranga, which is located on the eastern side of Sultanabad village. The soil consists of thin layers with varying texture from silt loam to sand. Several buried organic layers marks old floodplain surfaces. The groundwater level is closer than 1 m from the soil surface and may also reach the soil surface in old stream channels. The vegetation is dominated be seabuck thorn shrubs on the wettest parts of the floodplain. Intermediate stream terraces are grass covered with scattered pines and junipers. The soil has a 100% plant cover due to its moist top soil. A large part of Ranga is open grazing land. Some smaller areas have also been cultivated but are now left fallow. Gleyic Fluvisol from a frequently The soil ph varies from less than 5 in the wet scrubland to about 8 on the flooded area on Ranga Pasture open grassland. The nutrient content is low, especially K and Mg, and the topsoil organic matter content varies from more than 10% in the wet scrub areas to less than 2% in parts of the grassland. Low fertility and excessive wetness are limitations that restrict the agricultural use of area to animal grazing. Because of its accessibility from the upper villages, the Ranga is intensively used for grazing. Haplic Cambisols and Calcic Luvisols Cambisols are well-drained soils with weakly developed subsoil horizons. Luvisols are also well drained and characterized by the migration of clay particles from the surface horizons to a clay rich subsurface horizon. In the study area these soils are developed in loess covering glacial material. Haplic Cambisols are found in areas where the loess-layer is 1 m or more thick and where the loess-layer is about 50 cm thick over very rocky material. Calcic Luvisols occur where calcareous glacial till are found under the loess layer. The upper part of the glacial till is decalcified and enriched in clay. At about 1 m depth we can see secondary carbonates as white soft masses or as coatings on rocks. 3

Calcic Luvisol from Bondopiri pasture with a calcium carbonate rich subsoil These soils are common on both sides of the valley and are found from the valley floor up to about 3800 m elevation. Slopes are from 30 to 60%. The south facing valley side consists mainly of grazing areas. The soils are dry large part of the grazing season and the soil plant cover varies from 10 to 50%. The vegetation consists of scattered grasses and herbs and low juniper bushes. The north facing side is partly forested (pine). The plant cover varies from 60 to 100%, and an additional litter layer of pine needles preserve the soil moisture throughout the summer. Both soils have a silt loam surface texture. The loess layer has no coarse fragments but may have scattered rocks on the surface due to avalanches and smaller rock slides. Soils with this texture have a good water holding capacity, which means they have a better ability to retain plant available water than soils with higher sand content. On the other hand, wet silty soils are more subjected to soil compaction than sandy soils. The glacial till layer has a loamy texture with about 20% clay. Rocks and gravels are abundant. The topsoil ph range is 5.4 to 7.0 with 5.9 as a typical value for the forested side and 6.0 to 7.0 as a typical range for the south facing pasture side. The ph increases with soil depth. Organic matter content ranges from 2 to 5% with 3,6% as a mean value. These two soils are fertile soils compared to the other soils in the valley. But the south facing side is exposed to the sun and suffers from lack of soil moisture most of the growing season. New irrigation channels may turn this area into agricultural use, such as fodder production. The main problems are the steepness of the area and the high erodibilty of the silty soils. Hyperskeletic Leptosols Leptosols are either extremely shallow or have a high content of coarse fragments. The Leptosols in Basho consist mainly of gravels, rocks and boulders, and have less than 20% (by volume) fine earth material. 4

Hyperskeletic Leptosols are common in Basho valley. They consist mainly of rocks and boulders with a small amount of fine earth material in the interstices. Some of these soils have a thin loess layer at the surface. Most Leptosols are located on the escarpments of the glaciofluvial terraces and gullies where the fine material has been washed away by erosion. They are also commonly found on vegetated scree slopes. The escarpments are steeper than 60% and sparsely vegetated. The soil plant cover is often less than 5% and the most common plant species are artemisia, small juniper and wild rose bushes. The topsoil is dry most of the growing season and has very low organic matter content. These areas are sometimes grazed by goat herds. Pine forest on a rocky screefan toeslope The upper parts of the screeslopes are very steep and lack vegetation. The lower parts of the screefans have more gentle slopes and may support forest vegetation. Numerous small streams, either above or below ground, supply the soil with adequate moisture for natural rejuvenation of the forest to take place. The rocks and boulders may also give the tree saplings shelter from grazing animals. Haplic and Escalic Regosols Regosols are well-drained soils with no soil development other than a surface horizon with organic matter accumulation. Two different types of Regosols occur in the study area. Haplic Regosols are found in areas where the soil development is disturbed by mass movement such as rock slides and avalanches. The soils have a high content of rocks, but not as high as in Leptosols. Haplic Regosols are most common in the higher altitudes where the soils stay moist for a long time in the spring due to late snow melt. In the lower parts of the valley side they occur together with Cambisols and Luvisols. The organic matter content of the top soil increases with increasing elevation. The same trend applies to the soil plant cover which may be as low as 5% close to the valley floor and up to 100% in the high altitudes. Artemisia is a common plant species in the lower parts where the top soil is dry most of the growing season. The upper areas are dominated by carpets of low juniper bushes with open grassy patches in between. The upper parts of the valley side are important grazing areas for sheep and goats during the hot summer months. Agricultural terraces in Sultanabad village. Escalic Regosols are man-made soils formed as terraces. Most of the agricultural soils in the village and in the broqs are terraced. The agricultural soils in the village are nitrogen deficient and have a low organic matter content which ranges from 1.5 to 3.5%. The agricultural soils in the broqs are even more depleted of nutrients. Low input of nutrients and excess use of irrigation water are the most important reasons for the low fertility status. Abandoned agricultural terraces are found several places in the study area. 5

Haplic Arenosols Arenosols are well-drained soils with a sandy texture to a depth of 1 m or more. They are not common in the study area, but can be found in the uncultivated parts of the glacio-fluvial terraces. The soils have a low nutrient content and a very low water holding capacity, and are therefore not suitable for agricultural use. Haplic and Histic Gleysols Gleysols are poorly drained soils with groundwater within 50 cm depth some time during the year. They lack the layered profile that we see in Fluvisols. Gleysols are also uncommon in Basho Valley. They are found on the valley floor in the transition zone between the colluvial fans and the river flood plain. They are formed when water transported under ground on the fans reaches the flood plain and makes the ground water level rise to the surface. Histic Gleysols have an organic surface horizon while Haplic Gleysols have organic rich mineral soil at the surface. Gleysols are too wet for agricultural uses unless they are artificially drained. The Gleysols in Basho are undrained and only used for cattle grazing. A belt of Gleysols can be seen between Sultanabad village and Ranga, and at Soq broq. 6