Study On Spatial-temporal Variability Of Soil Properties In Coastal Region

At present, we are facing Shortage of arable land resources whose number is decreasing andoverall low quality of cultivated land in our country. Cultivated land is one of the most basicelements of agricultural production, the quality of which directly related to food security andsustainable agricultural development. As an important reserve land resources, tidal flat has a greatpotential of providing a lot of land resources for urban development and agricultural development.Due to the particularity of seabeach development, soil characteristics and land use have there owncharacteristics in reclamation area. Studying the characteristics and evolution law of spatial-temporal variability of soil properties in coastal region will help to improve crop cultivation,fertilization and management, also provide a scientific basis for the regional soil improvement,exploitment and utilization of seabeach resources and layout of agricultural production.Taking Cixi section of the coastal region in south Hangzhou bay as the study area, combinedwith the second soil survey data and soil updating investigation, spatial-temporal variabilitycharacteristics and laws of soil properties in the past30years were studied by the use of3Stechnology and geo-statistics. At the same time, three remote sensing images of1981,2002and2011were interpreted to obtain land use status and its change information. Then the effect oftemporal-spatial variability of soil properties on the land use types was discussed.The statistical results of soil properties show that soil organic matter and total nitrogen contentshowed the downtrend in the past more than30years. Soil available P content significantlyincreased from1981to2003, and decreased in the past10years. Available K content decreased,and it was relatively stable in the past10years. the total salt content and pH value also showed thedowntrend. Coefficient of variation of pH was smallest, and other soil indicators were highlyvariable, among which the variation coefficient of salt was biggest, followed by available P. Therewere great differences in soil properties due to the different reclamation history. The variationcoefficient of the soil properties decreased with the increase of reclamation time, and soilheterogeneity become weaker.The study on temporal-spatial variability of soil properties for1981,2003and2012in thestudy area found that soil organic matter and total nitrogen showed similar distribution with lowercontent in coastal late reclamation area. Available P and K showed block distribution, and their high-value and low-value areas had significant change. Available P content in Zhouxiang had beenhigh and the available K content the highest in coastal area.The total salt and pH were banded distribution, decreased with the increase of reclamationtime. The calculation results of change range of raster spatial distribution showed that the soilproperties changed greatly in space and time from1981to2012. Soil organic matter contentdeclined in78.18%regions from1981to2003, and45.03%declined from2003to2012. Thechange trend of soil total nitrogen was similar to organic matter. Soil available P significantlyincreased at an increase of more than4times,92.14%of the area showed downtrend in recent10years. From1981to200376.95%region’s soil available K decreased, the proportion of decreasemainly ranged from0to50%, from-50%to-50%in the recent10years. From1981to2003,59.71%region’s total salt content declined ranging from0to30%,92.82%showed downtrend inthe past10years. The soil pH value had the smallest change ranging from-10%to10%.