Investigation Of Nutrient Input And Fertilizer Recommendation Under Winter Wheat Summer Mazie Rotation System In Guanzhong Plain

Winter wheat/summer maize rotation is the main important cropping system inGuanzhong area of Shaanxi Province. Fertilizer plays an important role in increasing cropyield. However, in recent years crop yield was not increased with the increase in fertilizerinput, which indicates over-use fertilizer exists. This study, firstly, evaluated the presentsituation of farmer’s fertilizer application for winter wheat/summer maize rotation system,and secondly determined the status of soil nutrient content, and thirdly summarized nutrientsaccumulation at different stages of winter wheat/summer maize growth and nutrient supplycapacity of soil based on literature studies. Finally, combined with soil nutrient abundanceindex, soil nutrient status in the region, the current reasonable fertilization plan ofwheat/maize was established for different soil fertility levels. This fertilization plan could beused as formulae for fertilizer producer, in such way the rational fertilization would beenhanced.The main results obtained were as follows:1.The investigation of farmer’s fertilizer application under winter wheat and summermazie rotation system was carried out for more than1700households in10representativecounties of Guanzhong plain from2011to2012. The result showed that means of N, P₂O₅and K₂O application rates for winter wheat were210±106kg/hm²,183±121kg/hm²and25±49kg/hm², respectively, and the mean yield of winter wheat was6.5±1.0t/hm². The yieldof summer maize was6.2±1.2t/hm², and means of N, P₂O₅and K₂O application rates were290±115kg/hm²,45±88kg/hm²and12±30kg/hm², respectively. Based on previousstudies,there were about34percent of households whose N application rates were suitable,about3percent of households whose N application rates were far below the right amount,7.6percent of households whose N application rates were low,16.8percent of households whoseN application rates were high and38.5percent of households whose N application rates werefar above the right amount. For summer maize, there were more than75percent ofhouseholds whose N fertilizer was over application, and about11percent whose Napplication rates were suboptimal, and only about10percent whose N application rates werewithin the optimal range. Nitrogen, phosphorus and potassium nutrients were mainly appliedfor as base dressing for winter wheat, and the basal N rate accounted for90%of total N application. For summer maize, N, P₂O₅and K₂O nutrients were mainly applied for as topdressing at jointing stage, and the N rate of top dressing accounted for90%of total nitrogen.The partial factor productivity （PFP） of N, P₂O₅and K₂O were31.0kg/kg,35.5kg/kg and260kg/kg, respectively, for winter wheat, and were21.5kg/kg,137.8kg/kg and516.7kg/kgrespectively, for summer maize. In a word, under the winter wheat and summer maizerotation syetem in Guanzhong area, over application of nitrogen fertilizer is a big issue to besolved in future, and over application of phosphorus fertilizer should be paid more attention.2.The soil test results showed that the means of soil organic matter content were1.68%,the means of soil total nitrogen were1.13g/kg, the means of available nitrogen were95.8mg/kg, the means of available phosphate were20.2mg/kg, and the means of availablepotassium were169.2mg/kg. Based on soil nutrient abundance index, soil fertility levelbelonged to medium level, which accounted for a large proportion in this region for winterwheat and summer mazie rotation system. The N,P and K uptake for producing100kg grainwere1.64-4.40kg,0.19-0.83kg and1.22-4.27kg, respectively, for wheat, and1.44-3.91kg,0.16-0.67kg and0.76-3.67kg, respectively, for maize. The nitrogen uptake mainly occurredfrom seedling to regreening stage and from jointing to anthesis stage for winter wheat, andfrom seedling to jointing stage and from bell stage to grain filling stage for summer maize.According to the above results, proposed reasonable fertilization plan for wheat was135kgN/hm²and90kg P₂O₅/hm², respectively, in high fertility soil, and120kgN/hm²and75kgP₂O₅/hm², respectively, in medium fertility soil, and105kgN/hm²and60kg P₂O₅/hm²,respectively, in low fertility soil. For summer maize, proposed reasonable fertilization planwas120kgN/hm²in high fertility soil, and105kgN/hm²and45kg P₂O₅/hm², respectively, inmedium fertility soil, and90kgN/hm²and45kg P₂O₅/hm², respectively, in low fertility soil.The recommended P fertilizer would be applied as base dressing for both wheat and maize,and N fertilizer would be50%as basal fertilizer and50%as top dressing for winter wheat,and N fertilizer would be mainly as top dressing in jointing stage and bell stage, respectively,for summer maize. Nevertheless, the above fertilization plans should further test in farmer’sfield.