| This study used field fertilizer effect tests of main crops in different regions for many years in combination with a large number of household surveys to analyze the present situation and changes of compound fertilizer application among farmers in China and evaluate the development direction of the compound fertilizer industry on the basis of a total of 3602 farm households in China from 2004 to 2006 and from 2014 to 2016.Specifically,the results of 293 field fertilizer tests in 2001-2006 and 2008-2014 were analyzed to evaluate the agricultural effects of different production process of compound fertilizers.Results of 761 field fertilizer trials conducted in 2002-2006 and 2012-2016 were used to investigate the annual yield and change of main crops and their respective inter-annual variation of agricultural efficiency.The obtained results were used to optimize the formula of compound fertilizer and scientific fertilization technology,and to guide the addition of medium and micronutrient elements in the process of compound fertilizer production.The main findings are as follows:1.Based on a large number of farmer household surveys regarding fertilization,it was found that nitrogen,phosphorus and potassium contained in compound fertilizers accounted for 69.5%,92.1%and 84.3%of their total inputs in agriculture.The average fertilizers input ratio of nitrogen,phosphorus and potassium for grain crops was 1:0.36:0.30,and the average input ratio of nitrogen,phosphorus and potassium fertilizers for cash crops(vegetables and fruit trees)was 1:0.75:1.07.According to the analysis of census data,the application of compound fertilizer in China increased from 7.98 to 22.27 million tons during 1997-2016,with an average annual increase of 0.70 million tons.However,the annual growth rate of compound fertilizer application rate showed a declining trend in recent years,for example,the application amount of compound fertilizer has dropped from 7%in 2008 to 1.4%in 2016.2.Due to the difference of physicochemical properties of domestic compound fertilizers produced by different processes,the yield effect of compound fertilizers produced by different processes is also different.During 2008-2014,no significant difference of the spring maize yield between different compound fertilizer treatments and BB fertilizers were observed in northeast China;Treatments with nitro-ammonia,potassium hydrogen,high tower compound fertilizer and BB fertilizer had significantly higher winter wheat yield than those with pellet compound fertilizer;Treatments with nitro-ammonia,high tower and potassium hydrogen compound fertilizer treatments on summer maize had similar summer maize yields,which were significantly higher than those of the treatments with BB,pellet and slow-release compound fertilizer.In addition,the slow-release fertilizer treatment had significantly lower yields than that of the other compound fertilizer treatments on rice in northeast China.In south China the rice yield applied with BB,high tower and pellet compound fertilizer was significantly higher than those of other compound fertilizer treatments.Moreover,88.4%of tests applied with high-tower fertilizer increased the leaf vegetable yield by>30%,which was higher than the other compound fertilizers.Furthermore,86.1%of the field tests applied with nitro-ammonia compound fertilizer increased the vegetable yield by>30%,which was higher than the other compound fertilizers.3.With the wide use of compound fertilizer and the increase of fertilizer and nutrient input,the supply capacity of soils and the agronomic efficiency of fertilization also changed.In the cultivation area of spring maize in the northeast of China,annual increase of the soil supply capacity from 2002 to 2016 was 6.1%,in contrast the agronomic effect of fertilization decreased from 15.5kg·kg-1 in 2003 to 8.1%in 2016.For winter wheat in north China,the soil supply capacity increased gradually from 2002 to 2016,with an annual increase of 1.6%.The agronomic efficiency of fertilization decreased from 9.0kg·kg-1 in 2003 to 6.5kg·kg-1 2016,limiting factors for high production of winter wheat were in the order of nitrogen>phosphorus>potassium.For summer maize in north China,the soil supply capacity increased gradually with an average annual increase of 2.9%,and the agronomic efficiency of summer maize fertilization increased first from 9.4kg·kg-1 in 2002 to 13.1kg·kg-1 in 2010 and then decreased to 11.lkg·kg-1 in 2016.In south China,the supply capacity of paddy soils were relatively stable from 2002 to 2016,agronomic efficiency decreased slightly,which were stable about 9.0kg·kg-1 from 2007.4.With the change of soil supply capacity and fertilization efficiency,the yield effect of crop fertilization also changes,which directly affects the optimization and adjustment of compound fertilizer formula.According to the fertilizer effect function,the average nitrogen(N),phosphorus(P2O5)and potassium(K2O)dosages for the maximum yield in spring maize,winter wheat,summer maize,and early season rice in 2002-2006 and 2012 to 2016 were calculated.The optimal compounded fertilizer formula N-P2O5-K2O for spring maize was in 2006 18-14-14,and 28-8-10 in 2016,which was generalized from 16 groups of field tests,which for winter wheat was estimated to be 18-18-6 in 2006 and was 18-20-4 in 2016,for summer maize was estimated to be 22-8-12 in 2006 and was 24-6-10 in 2016,for early season rice was estimated to be 20-10-14.In northeast China application of 30kg·hm-2 ZnSO4·7H2O or 150kg·hm-2 MgSO4·7H2O with basal fertilization did not significantly increase the yield of spring maize.In north China,applying 30kg·hm-2 ZnSO4·7H2O with basal fertilization increased the yields of winter wheat and summer maize while the application of 30kg·hm-2 borax did not show significant impact on wheat yield.In south China,no significant impact on rice yield was observed when CaO was applied at a rate of 75kg·hm-2 with basal fertilization.5.Based on the yield effect of crop fertilization and optimization of compound fertilizer formulation,the fertilization reduction schemes for main crops were worked out through a large number of field tests.For spring maize,relative to the conventional application rates,the reduced fertilizer treatment containing basal fertilization of 525 kg·hm-2 and topdressing of 150 kg·hm-2 urea decreased the fertilizer input by 4.0%-17.2%and increased the yields by 0.1%-10.0%,achieving the purpose of reducing nutrients input and increasing nutrients use efficiency.For winter wheat,reducing basal fertilization rate from 750 to 600 kg·hm-2,or reducing topdressing rate by 25%did not influence the winter wheat yield significantly.For summer maize,for single fertilization as topdressing,20%reduction of an application rate of 750 did not decrease yield production but increase the economic benefit.For the strategy with 450kg·hm-2 as basal and 300kg.hm-2 as topdressing,20%reduction of the basal and 30%reduction of the topdressing,indicating a total reduction of 40.5%of fertilization,did not change yield production significantly.With the combination of seed fertilization and basal fertilization of 750 kg·hm-2,reduction of fertilization increased the yield by 3.8%and 15.1%.For rice in south of china,reducing basal fertilization rate of 375 kg·hm-2 by 20%,or the rate of 450 kg·hm-2 by 46%as well as reducing the topdressing rate of 225 kg·hm-2 by 25%all did not decrease the yield of rice.For vegetable,a 20%reduction of the topdressing rate of 375 kg·hm-2 for tomato and 600 kg·hm-2 for lettuce,and basal fertilization rate of 750 kg·hm-2 for pepper did not decrease their yields significantly yet increased the net benefit by 4.7-12.3%.In comparison with the basal fertilization rate of 600 kg·hm-2 for cabbage,reducing 20%of the rate but combined with organic fertilization rate of 375kg·hm-2 can ensure its yield.6.At last,soil supply capacity also affects the adjustment of crop fertilization methods.From 40 field tests,single fertilization did not show significant impact on spring maize yield comparing to multiple fertilization,but the single fertilization should be accompanied with seed fertilizer application less than 75 kg·hm-2 according to 7 field tests for single fertilization.Thirteen field tests confirmed that the strategy of single fertilization as basal for winter wheat was not recommended for wide use presently.There was not significantly difference in summer maize yield between single and multiple fertilization method in all 5 field tests.Fertilization strategy containing compound fertilizer 375 kg·hm-2 as basal and 300 kg·hm-2 at 2-leaf stage was recommended for direct seeded rice cultivation. |
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