| Characteristics of several soil types were systematically compared after investigation and experiment, at same time utilization status, specific and existing problem of soil resources were profoundly analyzed, the treatments of amendments and utilization were concluded according to result analysis of soil resources, and results were followed:1. Irrigation-silted soil is the main soil type in Honggu district of Lanzhou city along with loessial soil, sierozem and fluvo-aquic soil. Irrigation-silted soil is mainly distributed along the terrace 1 and terrace 2 in Datong river valley and Huangshui river valley. Irrigation was convenient, grain crops and economical corps are planted in this district, the area occupation rate of sierozem soil is 81.72%, the area is about 107.5 hectares in plain, and the altitude of sierozem soil is from 1590 m to 1770 m. The loessial soil was can be found in many places in the district, but the loessial soil is mainly distributed in Huangshui river valley, the area of loessial soil is about 126.4 hectares, the area occupation rate is about 3.11%. The area of fluvo-aquic soil is the minimum in the district, which is about 18.6 hectares, the area occupation rate is about 0.46%, the fluvo-aquic soil are mainly distributed along Honggu new village and Yiaojie red mountain village.2. The area of irrigation-silted soil is about 3814.1 hectares, the area occupation rate is about 93.79% in plain irrigation lands, Hongchijin soil is main soil type of irrigation-silted soil in the district, the area of Hongchijin soil is about 3597 hectares, its area occupation rate is 88.46%.The clay soil layer was existed in 32-77cm profile in Hongchijin soil, clay soil layer had a good effect of water retained and fertilizer retain, at same time it had a bad effect of water permeation and air permeation, the rate of solid particle to air and to soil water is not better for crops growth, resulting in leaves becoming yellow, root decay and seeding death.3. The rate occupation of less than 0.01mm soil particle size is 3.46%, the rate occupation of more than 0.01mm soil particle size is 66.54%, the rate occupation medium clay soil is 85.92%, the rate occupation light clay soil is 14.08%, the light clay soil is becoming heavy clay soil with the depth increase in soil profile.4. The soil pH value is 8.26 in plough layer, the CaCO3 content is varied from 8.44% to 14.17%, the average value is 11.44%, the alkaline limestone soil has good correlation with pH, pH has evident impact on activity and utilization of phosphorus, which result in the agriculture production decreased.5. The average salt content is about 0.1667% in 0-20 cm soil profile, the average salt content is about 0.1733%, 0.1974% and 0.1571 % under plough payer, in medium plough layer and at bottom of plough layer respectively, the medium plough layer has an evident salt accumulation, it is easy to come into being salinization under dry and bad drainage condition6. The soil nutrient status is lack of nitrogen, less phosphorus, rich kalium and low organic matter. Soil nutrient in order of is Pingan town > Huazhuang town > Hezui rural > Honggu rural > Haishi town > Yaojie town > Ping platform. The regression analysis showed that the content and distribution of soil nutrients had a significant linear correlation with crop yield.7. The tillage soil can classified to 4 grades, according to principles of soil resources evaluation and the correlation between occurrence, development process, quantity, quality, distribution, physic-chemical properties with environment,. The area of Hongjin soil, Huangjin soil and Huicha soil is 636.2 hectares in grade 1, the area occupation rate of Hongjin soil, Huangjin soil and Huicha soil to whole farming lands is 54.43%, distributing in terrace land terrace 2 lands, and the altitude is from 1590m to 1770m. The thick irrigation-silted permeation sandy soil, thin irrigation-silted permeation sandy soil, thin irrigation-silted accumulation sandy soil, bottom fluvo-aquic sandy soil, medium fluvo-aquic soil, terrace loessial soil and terrace white loessial soil are classified in grade 2, the total area of those soil types is 1534.3 hectares, the area occupation rate is 22.97%, mainly distributing from terrace 1 lands to terrace 4 lands, and the altitude is from 1590m to 940m. The mountain sierozem soil, tillage loessial soil are classified in grade 3, the total area is 1742.4 hectares, the area occupation rate is 6.08%, distributing in mountains and hilly and plain lands, and the altitude is from 1800m to 2100m. The salty irrigation-silted soil are containing kraft chloride and sulphate in grade 4, the area is 17.7 hectares, the area occupation rate is 0.026%, 8. The improvement measures of several agriculture soil types8.1 Irrigation-silted soil: farmlands soil, sandy and organic matter should be added to thick irrigation-silted Hongjin soil, dam construction should be used for land reforming and increase soil layer for thin irrigation-silted, the underground water level should be controlled to avoid salinization, less amount of irrigation water should be supplied with more times, at same time canal seepage should be controlled.8.2 Fluvo-aquic soil: irrigation agriculture should be developed in terrace and sloppy lands in irrigation regions, adding organic fertilizer in order to promote the land productivity; mulching plant and terraced field plant should adopted to promote soil water storage in no irrigation areas; slope cropland should be converted to woodland and grassland in hilly region, in order to avid the high water and soil loss, and land soil fertility decline in the region.8.3 Fluvo-aquic soil: digging drain ditch in order to low underground water level, ploughing firstly, sunning soil and weeding control in mid-summer secondly, organic fertilizer supplying and high height stubble standing and returning straw to soil thirdly, crop arrangement patterns adapting according to soil fertility status, coupling land utilization and land cultivating fourthly,8.4 Loessial soil: building terraces farmlands, planting trees and grass, soil and water conservation, strengthening drought resisting and increase soil water storage, green manure crops and bean crops are planting. |
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