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1. Institute of Geographical Sciences, Henan Academy of Sciences, Zhengzhou 450052, China; 2. Henan Kefa Geographical Research Institute Co., Ltd., Zhengzhou 450052, China

Abstract　In order to explore the effects of farmland quality evaluation on site selection of land consolidation projects, the methods of agricultural land use classification were used. Taking several project areas in Yanjin County of Henan Province as examples, the farmland quality before and after land consolidation projects was evaluated. The results indicate that under the conditions of reasonable site selection, the implementation of land consolidation projects can effectively improve the farmland quality and increase the grain productivity. Therefore, before the site selection for land consolidation projects, it is recommended to carry out pre-evaluation of farmland quality, and guide the project implementation according to the evaluation results. Besides, it is recommended to focus on medium and low level farmland with large centralized area, excellent original production conditions, but low level of development and use.

Key words　Farmland quality, Pre-evaluation, Land consolidation, Site selection

1　Introduction

Land consolidation refers to the activities of consolidation for land with low efficient use, irrational use, non-use or production and construction activities and damage to land caused by natural disasters, and a main purpose of land consolidation is to increase the grain productivity and make contribution to ensuring national grain security through improving the farmland quality[1-3].

Before the implementation of land consolidation projects, it is required to firstly solve the problem of site selection, because proper and scientific site selection is an essential guarantee for bringing into play the project benefits[4-8]. In China, the studies on site selection of land consolidation projects focus on qualitative analysis of the natural, social, and economic conditions affecting site selection[9-11], while there are few quantitative studies, and there are no factors that give prominence to the farmland quality[12-14].

The farmland quality is a comprehensive reflection of the various properties of farmland, and it is an essential indicator for evaluating whether the farmland consolidation can increase the grain productivity and how much it can increase the grain productivity[15-17]. At present, Henan Province evaluates the farmland quality after the completion of the consolidation projects and before the acceptance of the projects. Taking several project areas in Yanjin County of Henan Province as examples, we analyzed changes after implementation of land consolidation projects, and recommended that the farmland quality evaluation should be carried out in advance. Specifically, the farmland quality should be evaluated before determining the site selection, and take the optional sites with maximum increase in grain productivity as the target of priority selection. In addition, we pointed out some classification factors that can be significantly improved after land consolidation projects, so as to provide more pertinent theoretical basis for subsequent project design.

2　Research area

Yanjin County is a traditional agricultural county in the northern part of Henan Province, located in the Yellow River and Haihe River Basin. Covering an area of 886 km2with 500 000 people, Yanjin County includes five towns, seven townships, 345 administrative villages (residential committees), and one provincial-level industrial agglomeration area, and it is an advanced county of grain production and high quality wheat industrialization demonstration county in China. It has obvious advantage of agricultural resources, and grain crops are mainly wheat and maize.

Henan Province launched the Key Project for Land Consolidation of Canal Head in and along South-to-North Water Diversion in 2010, to increase farmland and yield through land consolidation. As an important agricultural county, Yanjin County was included into this key project. According to the project implementation plan, the fourth year works of Yanjin County (Phase 1) project area II includes four areas: Yulin, Wanglou, Weiqiu and Dongtun. Yulin area has the geographic coordinates of 35°11′22″-35°16′13″ N and 114°01′54″-114°07′42′ E; Wanglou area has geographic coordinates of 35°13′28″-35°18′48″ N and 114°18′18″-114°24′08″ E; Weiqiu area has geographic coordinates of 35°17′53″-35°19′29″ N and 114°22′13″-114°24′41″ E; Dongtun area has geographic coordinates of 35°20′18″-35°22′03″ N and 114°06′19″-114°08′43″ E, as shown in Fig.1.

Fig.1Mapforlocationofeachprojectarea

3　Research methods and basic parameters

3.1ResearchmethodsEach project area is treated as an independent area, and each project area adopted the agricultural land classification method. Under the control of the standard farming system, we used the light-temperature production potential (or climate production potential), natural quality of farmland, land use level, and land economic level to make correction to generate the farmland evaluation classification index, and divided the farmland to different classifications according to the evaluation classification index, and calculated the changes in corresponding farmland quality potential (grain productivity).

According to theProceduresforClassificationQualityofAgriculturalLand(GB/T 28407-2012), after simplifying the relevant formulas, the calculation method of the agricultural land classification index can be expressed by the following formula:

(1)

whereGidenotes the agricultural land classification index of thei-th classification unit,αijdenotes the light-temperature (or climate) production potential index of thej-th crop,CLijdenotes the agricultural land natural quality of thej-th designated crop in thei-th classification unit,βjdenotes the yield ratio coefficient of thej-th crop,Klijdenotes the land use coefficient of thej-th designated crop in thei-th classification unit, andKcijdenotes the land economic coefficient of thej-th designated crop in thei-th classification unit.

3.2Basicparameters

3.2.1Division of evaluation units of each project area. According to the determination principle of the evaluation units, the four areas were divided into seven evaluation units: Yulin area was divided into three evaluation units because there were obvious differences in some factors such as soil organic matter content and some areas were not adjacent in space; Wanglou area was divided into two evaluation units because the area was large and some factor indicators were different; both Weiqiu area and Dongtun area were divided into one evaluation unit, as listed in Table 1.

Table 1　Division of evaluation units in each project area

3.2.2Standard cropping system. The standard cropping system refers to the local stable cropping system formed in local normal climate and soil conditions. Specifically, it is two crops each year: winter wheat-summer maize.

3.2.3Benchmark crops and designated crops. According toProceduresforClassificationQualityofAgriculturalLand, the benchmark crop of Yanjin County is winter wheat and designated crops are winter wheat and summer maize.

3.2.4Production potential index. Paddy field and dry land (irrigated land) with irrigation conditions fully meeting the requirements of crop growth applied the light-temperature production potential; dry land without irrigation conditions applied climate potential; dry land (irrigated land) with irrigation conditions not fully meeting the requirements of crop growth applied the production potential index of the land parcel through interpolating between the light-temperature production potential and climate production potential according to the probability of irrigation. In this study, the irrigation conditions of all project areas can fully meet the requirements of crop growth, so the light-temperature production potential was applied. The light-temperature production potential of winter wheat was 1 410, while the light-temperature production potential of summer maize was 1 860.

3.2.5Yield ratio coefficient of designated crop. According to the result of supplementation and improvement of farmland quality in Henan Province in 2011, the yield ratio coefficient of winter wheat was 1, and the yield ratio coefficient of summer maize was 0.890 1.

3.2.6Classification factors and weight. The classification factor indicator area refers to the applicable area of the evaluation indicator system composed of the classification indicators for calculating the agricultural land natural quality. According toProceduresforClassificationQualityofAgriculturalLandand the result of supplementation and improvement of farmland quality in Henan Province, the classification factor indicator area of Yanjin County was the northeast low plain area of Henan Province. The classification factor system was determined by the classification factor indicator area, as listed in Table 2.

4　Result analysis

4.1AnalysisonchangesinclassificationfactorsThrough field surveys and soil sample collection tests, we obtained changes in classification factors of project areas after the construction of land consolidation projects (Table 3). From Table 3, after the implementation of the project, the probability of irrigation, drainage condition and profile pattern showed the largest changes, and there was basically no change in other factors. Reasons are as follows. (i) Through the construction of farmland water conservancy projects, it increased the probability of irrigation of some project areas (mainly Yulin area). Under the condition that the water source is guaranteed, the lower the original probability of irrigation, the more significant improvement effect it had after the implementation of the project. (ii) Through building and improving the drainage system, it improved the field drainage conditions and increased the score of drainage conditions in most areas. (iii) Through the land consolidation and backfilling projects, it improved the profile pattern of some farmland and slightly increased the score. In addition, the topsoil texture, soil organic matter content, soil pH and salinization degree are inherent features of soil, they would have small changes only under some certain conditions in a long term, thus they are basically not subject to the construction of projects.

Table 2　Crop classification factors and weight

Table 3　Changes in classification factors of project areas after land consolidation

4.2AnalysisonchangesinclassificationWe calculated the average national classification index of the farmland of each project area using the area-weighted method and following formula:

Yaverage=∑(YiSi)/S

(2)

whereYaveragedenotes the average national classification index of farmland of the project area before/after the construction,Yidenotes the classification index of thei-th farmland parcel in the project area before/after the construction,Sidenotes the area of farmland parcel in the project area before/after the construction, andSis the total area of farmland in the project area before/after the construction.

Based on the calculated average national classification index of farmland, the farmland was divided into corresponding national natural classification, national use classification, and national economic classification. Taking the national use classification as an example, we analyzed changes in each project area after the land consolidation projects. The changes in national classification index and average national use classification were listed in Table 4. After the implementation of the consolidation projects, the average national use classification index of all project areas had certain level of increase, Dongtun area and Yulin area had the largest increase (by 153 and 127 respectively), and the corresponding average national use classification increased one level. The comprehensive production conditions (such as drainage conditions and probability of irrigation) of these two areas were worse before consolidation, thus the improvement of farmland production conditions was most effective after consolidation. For Wanglou area and Weiqiu area with excellent field production conditions before consolidation, the consolidation projects had limited improvement effect and mainly played the role of consolidating the original productivity. The average national use classification index showed certain increase, but there was no change in average classification.

Table 4　Changes in national farmland use classification in project areas after implementation of consolidation projects

4.3AnalysisonchangesinproductivityFrom the conversion relationship between the national use classification and productivity, 1 500 kg/ha farmland productivity corresponds to 3 000 national use classification index. Through the total farmland area of all project areas and the increased average national use classification index after consolidation, we calculated the increased average total productivity of each project area (Table 5). From Table 5, it can be seen that after the implementation of the consolidation project, the largest increase in the average total productivity was Yulin area, because both the increase of average classification index and the total farmland area of this project area were large. The increase in average classification index of Dongtun area was large, but the total farmland area was small, so the increase in productivity was small. For Wanglou area and Weiqiu area, the increase in average classification index was very small, so the increase in productivity was also very small.

Table 5　Changes in average productivity of production areas after implementation of consolidation projects

5　Conclusions and recommendations

5.1Conclusions

5.1.1Through the implementation of land consolidation projects, especially land leveling projects, farmland water conservancy projects and field drainage works, it can effectively improve field production conditions and improve the farmland quality. The increase is related to the original production conditions of the farmland. For the farmland with better original conditions, the effect of the consolidation projects is limited, mainly playing the role of facilitating the field production and consolidating the existing level of productivity. For the farmland with poor original conditions, the effect of the consolidation projects is also limited, because the harsh conditions limit the engineering facilities to play their due role, such as the construction of irrigation projects in places where water is in short supply is of no great significance. For the area with excellent original productions but not well developed and utilized, the effect of consolidation projects can be fully realized.

5.1.2A main purpose of the implementation of land consolidation projects is to increase the grain production level and increase the grain productivity. However, the increase in grain productivity is jointly determined by the total farmland area and the increase in farmland classification. Therefore, when evaluating the benefits of different projects, it is required to consider both the total farmland area and the increase in farmland classification.

5.2Recommendations

5.2.1The farmland quality classification should be evaluated in advance. The farmland quality should be evaluated before determining the site selection, and it is recommended to take the optional sites with maximum increase in grain productivity as the target of priority selection, so as to carry out other feasibility researches.

5.2.2It is recommended to provide pertinent support works and facilities. On the basis of the farmland quality classification pre-evaluation, it is recommended to provide pertinent consolidation projects according to original production conditions, for example, increasing the probability of irrigation through building farmland water conservancy projects, reducing the terrain slope through land leveling projects, and improving the drainage conditions through building drainage facilities.

5.2.3It is recommended to strengthen the consolidation of medium and low classification farmland. Besides, it is recommended to focus on medium and low level farmland with large centralized area, excellent original production conditions, but low level of development and use. In addition, for high classification farmland with potential having been fully played, it is recommended to improve and provide corresponding works and facilities.

5.2.4It is recommended to implement large land consolidation projects. If the funds are limited, the land consolidation projects should not be fully launched in large areas. Instead, it is recommended to make joint effort to consolidate areas with high production potential and large centralized land. Such method is also consistent with the national policy of giving priority to the development of key large land consolidation projects.