Productivity Evaluation Of Farmland In Gully Region Of Loss Plateau

Loess Plateau is quite high, steep, and serious soil erosion, and has few resources available arable land. The soil productivity assessment on the Loess Plateau area can identify the fertility status and levels of the soil, optimize the allocation of resources and to promote the sustainable agricultural development. This paper selected Fuxian County of Shaanxi Province as the reseach object, with Geoway, ArcGIS, County Land Resources Management Information System and other softwares, using the land use map, soil map and related data sampling points, based on the evaluation of Fuxian County farmland classification and focus on the cultivated soil properties Fuxian analysis. Main results obtained are as follows:(1) The evaluation units of the spatial database consisted of the overlayed patches the current land use map and the soil map, and then assigned. Applying the Delphi method, 15 indicators have been chosen to evaluate cultivated lands. The determination of each associated weight was conducted by AHP. Adopting fuzzy mathematics method, in terms of their characteristics and different influence to cultivated land, set up subjective functions.Meanwhile, applying the accumulated model, the paper calculates the integrated fertility index of cultivated land, 0.52~0.87, in the last place and prints the output with the support of GIS software, thus finish the appraisal by dividing the fertility of cultivated lands within Fuxian into five grades.(2)The total cultivated area of Fuxian County is 49338.40hm2, of the total land area of 11.73%. The area of the first grades is 3649.32hm2, 7.40% of the total farmland area, the second is 13271.20hm2, 26.90% of total area, the third is 17416.04hm2, 35.03% of the total area, the fourth is 12047.58hm2, 24.42% of the total area, and the fifth is 2954.25hm2, 5.99 of the total area.(3)The first grade area of Fuxian is mainly on the both sides of the Hulu River, and the Loess Plateau is also scattered. The main soil types are loessialsoil and gray cinnamonic soil. The average land elevation is about 1146m, and the average slope is 7°. This area is gentle in Fuxian County , irrigation capability, and higher soil nutrient content. The second grade area of Fuxian is mainly plateau region and the both sides of the Luo and Hulu River terrace. The main soil types are cumulated irrigated soils, loessialsoil and gray cinnamonic soil. The average land elevation is about 1121m, and the average slope is 7°.This area is gentle in Fuxian County also. The third grade area of Fuxian is mainly on the loess plateau and the mountain ridge of gentle slope, part on the river trail. The average land elevation is about 1132m, and the average slope is 11.8°. The area whose slope is steeper than 7°83.12% of the total third grade area. The fourth grade area of Fuxian is mainly on the hilly region and the plateau gully regions, partly on the loess plateau. The average land elevation is higher than the second grade, about 1146m, and the slope is steeper also. The slope of the most fourth grade is more than 3°, and the average slope is 18°. The main soil types is loessialsoil. The fifth grade area of Fuxian is mainly on the rocky mountain in northeast of Fuxian County and the steeper plateau gully regions. The average land elevation is about 1137m, and the smallest slope is 11°, the highest slope is 43°, the average slope is 24°. The main soil types is loessialsoil.(4)From the geographical features distribution of the cultivated land, the level of Fuxian cultivated land and topography, soil types, slope are closely related, showing a distinct geographical distribution. With the fertility level increased, the landscape types from more flat plateau in the ditch and river transite to the higher elevations of the mountain and shoaly land made of the new alluvial (or pluvial).(5)The soil types of Fuxian are mainly loessialsoils and gray cinnamonic soil, with the dark loessial soil and cumulated soil also in a small distribution. In addition to soil organic matter and nutrient content than those outside the country increased during the second survey, but the average content was still low, poor soil fertility. The soil structure of Fuxian is good, with pellets, lump, nuclear shape and edge blocks mainly. Soil texture is also good with the light loam and loam more.