Evaluation on ecological value of arable land in hilly land consolidation region of Shandong province

Arable land not only has important agricultural production function and economic value, but also has ecological function and value, such as gas regulation, nutrient cycling, water conservation, soil conservation etc. But it is difficult to have quantitative evaluation on it. Low hills are important land consolidation areas in China, engineering and biological measures taken during land consolidation change the arable land area, soil properties, terrain slopes, irrigation conditions etc, which leads to changes in the ecological value of arable land in project area. Taking the Lixin land consolidation project of Laiwu city in Shandong province as an example, based on the ecological service value evaluation theory, the evaluation methods of arable land ecological value was proposed, the four ecological service values were calculated, including gas regulation, nutrient cycling, water conservation and soil conservation, and their values before land consolidation in low hilly region were compared with those after land consolidation in this paper.Gas regulation value was estimated by using carbon sequestration-oxygen making of crop and the substitution method. Before land consolidation, when the study area had no irrigation, peanuts were planting outdoors, biomass was lower, gas regulation value was 2.1848 million Yuan. After land consolidation, gas regulation value was 4.9441 million Yuan, the increase was 2.7593 million Yuan for production conditions improvement, mulching planting peanuts and biomass substantial increase. Nutrient recycling value was estimated by using soil pool nutrient cycling and market pricing method. After land consolidation, arable land area and soil thickness increased significantly, soil bulk density decreased and soil nutrient content decreased slightly. Nutrient cycling value was 1.3082 and 1.5855 million Yuan before and after land consolidation respectively, the increase was 277,300 Yuan after land consolidation. Water conservation value was estimated by using water conservation and market pricing method. For the study area was mainly sandy loam and lack of irrigation facilities, water conservation value was 88,900 Yuan before land consolidation. After land consolidation, water conservation value was 425,600 Yuan, and the increase was 336,700 Yuan for soil texture was slightly improved and new water storage facilities were built. Soil conservation value was estimated by using the amount of soil nutrients remains and market pricing method. The study area was hilly area, so range of terrain slopes were relatively large. Taking different measures, such as land leveling, setting up the sloping terrace, etc., the soil erosion was reduced and soil nutrients were maintained. The amount of potential soil erosion, realistic soil erosion and soil conservation were measured with universal soil loss equation (USLE) before land consolidation, then soil conservation value were obtained, which were 704,200 Yuan. The same method was used to calculate the soil conservation value after land consolidation, the value was 793,600 Yuan.The total ecological value, which was equal to the sum of gas regulation, nutrient cycling, water conservation and soil conservation was 4.3132 and 7.8103 million Yuan before and after land consolidation. The results showed that arable land had higher ecological value and among them, gas regulation value was the maximum. The arable land ecological value increased 3.4971 million Yuan and its growth rate was 81.03% after land consolidation, so the ecological benefit of land consolidation was prominent. The evaluation method provides a reference for arable land ecological evaluation, and the evaluation results provide a scientific basis for performance evaluation of land consolidation project in Lixin of Laiwu city.