| The study aimed to explore the spatial variability and pattern of soil nutrients in countyfarmland, and provide a scientific guidance for cultivated land maintenance,and maintain andimprove the productivity of arable land regional agricultural development in the hilly regionof Shaanxi. This paper took the Zhen’ an county of Shaanxi as the study area, with the supportof survey of soil fertility and quality evaluation in Shaanxi Province from2010to2011.Geostatistics combined with geographical information system(GIS) was applied to study thebest semi-variance theory model and to analyze ordinary Kriging interpolation of availablePotassium in soil based on the data of2283soil samples in the0-20cm topsoil in farmlandof19towns. And based on GIS technology platform, with comprehensive utilization ofgeostatistics, Delphi method, comprehensive evaluation method, etc, at the same time,,establish Zhan’an County cultivated land fertility evaluation system and wheat plantingsuitability evaluation system.The main conclusions are as follows:(1) The spatial autocorrelation of soil organic matter、total nitrogen、available nitrogen、available phosphorus and available potassium in Zhen’ an County farmland all belonged tomiddle intensity. Those soil properties had different spatial correlations, AP had the weakspatial correlations, SOM、AN and TN had the moderate spatial correlation, and AK had thesignificant spatial correlation.Spatially, soil nutrients were significantly lower in the centralsection than around SOM contents, ranged from4.60to37.80g/kg, concentrated at17-20g/kgwith an average of18.27g/kg which was increased by40.54%compared with that in1980(13.00g/kg). TN contents ranged from0.31to2.18g/kg, concentrated at1.0-1.2g/kgwith an average of1.09g/kg which was increased by17.20%compared with that in1980(0.93g/kg). AN contents ranged from20.90to179.00mg/kg, concentrated at90-100mg/kg with an average of97.47mg/kg which was increased by57.21%compared with that in1980(62.00mg/kg). AP contents ranged from2.46to47.50mg/kg, concentrated at17-20mg/kg with an average of16.27mg/kg which was increased by125.97%compared with thatin1980(7.20mg/kg). AK contents ranged from27.00to246.00mg/kg, concentrated at120-130mg/kg with an average of122.09mg/kg which was increased by47.10%comparedwith that in1980(83.00mg/kg). The mean ratio of C to N was9.84. The mean ratio of N to P was4.00. The content of SOM, TN and AK were in middle level, while the AN and AK weremore than middle level. The mean ratio of soil nutrients was in imbalance state. Therefore, itis necessary to put forward a plan which guide farmers rational fertilization and improvefertilizer utilization ratio.(2) The area of farmland in the study area is28613.26hm2,8.21%of the total land area.The third level of farmland has highest distribution which is12790.45hm2, accounting for44.70%of the total cultivated area. The next is the forth level of farmland, it’s area is7353.36hm2, accounting for25.70%of the total cultivated area. The area of the first level farmlandis3997.18hm2, accounting for13.97%of the cultivated area.The area of the second evelfarmland is4156.28hm2, accounting for14.53%of the cultivated area. The fifth level offarmland is least, accounting for1.10%of the cultivated area. The most of the first and secondlevel of farmland placed in Valley and plain regions,the most of soil types are yellow brownand limestone soil. The third level of farmland is largely distributed in hilly region and majorsoil type is yellow brown. The forth level of farmland is distributed in hilly region and majorsoil type is yellow brown.The fifth level of farmlang major places in hilly region and middleand high mountain regions, and major soil type is regosols and new soil(3) For wheat, in Zhan’an County the content of total organic matter is high, thealkali-hydrolysable nitrogen is low, the available phosphorus is medium, the available K ishigh. The suitability level of cultivated land of wheat in this County is different, highlysuitable for arable land accounts for19.93%of the total arable land area, suitable accounts for21.54%, both distribute along the river terrace; marginally suitable accounts for47.46%,; notsuitable accounts for11.07%, distributes in hilly region.It should be reasonably increased thecontent of available phosphorus, maintain the content of soil available potassium and soilorganic matter, at the same time,pay attention to reform soil structure, increase the ability ofsoil drought resisting, fertilized retaining and fertilizer capacity, further enhance the suitabilityof wheat cultivation. |
PDF Full Text Request