| Alluvial soil is mainly distributed in North China Plain where the alluvial soil accounts for 53% of the total amount in China. Food production in this area makes 22% of total national grain output and plays an important role in food security in China. It is of great significance to carry out the research on evaluating the alluvial soil fertility and spatial variability of soil indicators to protect agricultural resources and to ensure food security.In this paper, Shenzhou was selected to be the research area in Hebei Province. With local production conditions considered, pH, organic matter (OM), total nitrogen (TN), available phosphorus (AP), available potassium (AK), salinity, cation exchange capacity (CEC), bulk density (BD) and Profile Structure were chosen as evaluating indexes. The study of spatial variability of fertility was based on the principle of geostatistics spatial supported by GIS and computer technology. On this basis, utilizing neural network algorithm to determine the index weight, combined with fuzzy comprehensive evaluation model to determine the level of land fertility, and developing the distribution of soil indicators variability and fertility level by GIS were used to provide a theoretical basis for improving soil fertility and sustainable use of alluvial soil resources in North China Plain.1. Statistical analysis of soil fertility indicators indicated that coefficient of variation for soil nutrients (CV) varied from 2.0% to 49.6%, among which pH and BD was weak variation (CV<0.15) and AP was strong variation (CV>0.35), with other middle variation fertility indicators. The order of CV was pH0/(C0+C1) of pH, AP and salinity were less than 25%, which implied a strong spatial dependence. The C0/(C0+C1) of OM, TN, AK, CEC varied from 25% to 75%, which was moderate spatial dependence. Range of indicator was from 4960 m to 16800 m, and the order was AP< OM25.0g/kg, fourth-grade-leveling area for OM accounting for 97.2% of the total cultivated land; TN range was 0.422.0g/kg, fourth and fifth grade area for TN accounting for 90.4%. AP range was 1130mg/kg, three grade area for AP accounting for 50.3%. AK range was 21220mg/kg, three and four grade for AK accounting for 89.5%.4. Fuzzy comprehensive index (IFI) was used to comprehensively evaluate fertility. The results showed that overall level of soil fertility was low in Shenzhou county.There was no first grade arable land (IFI>0.75), and the second grade arable land (0.65 |
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