| On account of the status of fertilization is not clear, the fertilizer structure is unknown for different crops in the different regions, fertilization effect has changed greatly at present in agricultural production in Shaanxi province. The study used the data from the project of soil testing and formulated fertilization and literature to evaluate the current status of fertilizer application and the spatial and temporal variations of chemical fertilization at the farmers' level, and variations of soil fertility from the 1970 s to the 2000 s in Shaanxi, which revealed the problems of nutrients input at present and put forward countermeasures to solve the problems, and provided the scientific basis for rational improvement fertilization technology. The main results are listed as follows:(1) In Weibei dry plateau, Guanzhong irrigated area and Qin-Ba mountain area of southern Shaanxi, the yields of wheat were 4269, 6437 and 3742 kg/ha, and the average yield of the whole province was 5334 kg/ha. Inorganic N, P2O5 and K2 O inputs averaged 183, 110 and 21 kg/ha respectively and PFP(Partial factor productivity) of N, P2O5 and K2 O were 35.02, 51.17 and 134.60 kg/kg respectively for the whole province. Compared with the rational levels of fertilizer rates, the ratio of households using excessive inorganic N inputs was 68.4%, and the excessive amount was 53,700 tons; the ratio of households using excessive inorganic P2O5 were 41.0%, and the excessive amount was 21,700 tons; the ratios of households using insufficient inorganic N, P2O5 and K2 O inputs were 5.6%, 38.1% and 77.5% for the whole province. Organic manure inputs were very low, and the ratio of households who used organic manure was 23.7%. Wheat yield could be increased by 249,000 tons if the households fertilizing with insufficient level of inorganic NPK fertilizers increased the fertilization rate to a rational level. In addition, it was not the most productive varieties that were the most grown in the three regions. The current status of household fertilization on wheat in Shaanxi province was that nitrogen fertilizer inputs was excessive, phosphate fertilizer inputs were both excessive and insufficient, and potassium fertilizer and organic manure inputs were both insufficient.(2) In Loess plateau area of northern Shaanxi, Weibei dry plateau, Guanzhong irrigated area and Qin-Ba mountain area of southern Shaanxi, the yields of maize were 7867, 7077, 6886 and 4872 kg/ha, and the average yield of the whole province was 6779 kg/ha. Inorganic N, P2O5 and K2 O inputs averaged 230, 63 and 20 kg/ha respectively and PFP of N, P2O5 and K2 O were 32.87, 113.17 and 228.90 kg/kg respectively for the whole province. Compared with the rational levels of fertilizer rates, the ratio of households using excessive inorganic N inputs was 63.2%, and the excessive amount was 65,900 tons; the ratio of households using excessive inorganic P2O5 was 30.8%, and the excessive amount was 12,000 tons; the ratio of households using insufficient inorganic P2O5 was 58.8%, and the insufficient amount was 30,800 tons; the ratio of households using insufficient inorganic K2 O inputs was 83.0% for the whole province. Organic manure inputs were very low, and the ratio of households who used organic manure was 36.9%. Maize yield could be increased by 1,024,600 tons if the households fertilizing with insufficient level of inorganic NPK fertilizers increased the fertilization rate to a rational level. In addition, it was not the most productive varieties that were the most grown in the four regions. The current status of household fertilization on maize in Shaanxi province was that nitrogen fertilizer inputs was excessive, phosphate fertilizer inputs were both excessive and insufficient, and potassium fertilizer and organic manure inputs were both insufficient.(3) The ratio of households who used organic manure in Loess plateau area of northern Shaanxi, Weibei dry plateau and Guanzhong irrigated area in apple orchards were 99.96%?24.52% and 20.37% respectively, whole province averaged 50.15%. The rates of chemical fertilizer NPK from Loess plateau area of northern Shaanxi,Weibei dry plateau to Guanzhong irrigated area all had an increasing trend, the amount of nitrogen fertilizer increased from 490 to 619 kg/ha, the amount of phosphate fertilizer increased from 318 to 447 kg/ha and the amount of potassium fertilizer increased from 73 to 382 kg/ha. Compared with the level of fertilizer rates, in Loess plateau area of northern Shaanxi, Weibei dry plateau and Guanzhong irrigated area, for chemical N application, 18%, 17% and 12% were rational respectively, whole province averaged 17%, 67%, 74% and 78% were excessive respectively, whole province averaged 72%; for chemical P2O5 application, 12%, 27% and 15% were rational respectively, whole province averaged 20%, 42%, 52% and 65% were excessive respectively, whole province averaged 50%; for chemical K2 O application, 11%, 12% and 14% were rational respectively, whole province averaged 12%, 84%, 48% and 15% were insufficient respectively, whole province averaged 56%. The current situation of household fertilization in apple orchards in Shaanxi province included: nitrogen fertilizer inputs was excessive, phosphate fertilizer inputs was both excessive and insufficient, potassium fertilizer and organic manure inputs were both insufficient.(4) In Loess plateau area of northern Shaanxi and Qin-Ba mountain area of southern Shaanxi, the yields of potato were 23.0 t/ha and 15.4 t/ha, and the average yield of the whole province was 22.3 t/ha. The rates of chemical fertilizer N, P2O5 and K2 O were 155, 78 and 13 kg/ha respectively in the whole province, which shows diminishing returns trends, and PFP of chemical fertilizer N, P2O5, K2 O were 183.66, 402.42 and 561.75 kg/kg respectively. Compared with the rational fertilizer rates, in Loess plateau area of northern Shaanxi and Qin-Ba mountain area of southern Shaanxi, for chemical N application, 43.0% and 4.0% were rational respectively, the average of the whole province was 39.4%; 24.5% and 50.3% were excessive respectively, the average of the whole province was 26.9%. For chemical P2O5 application, 64.6% and 16.0% were rational respectively, the average of the whole province was 60.1%; 21.9% and 56.0% were excessive respectively, the average of the whole province was 25.0%. For chemical K2 O application, 96.9% and 93.1% were insufficient respectively, the average of the whole province was 96.6%. The current situation of household fertilization on potato in Shaanxi province was that the nitrogen and phosphate fertilizer inputs were both excessive and insufficient, and the potassium fertilizer and organic manure inputs were both insufficient.(5) In Qin-Ba mountain area of southern Shaanxi, the average rice yield was 7822 kg/ha per year, and the ratio of households who got the yield up to medium level was 50.9%. The rates of total N, P2O5, K2 O were 169, 68 and 54 kg/ha respectively, and the rates of chemical fertilizer N, P2O5, K2 O were 159, 62 and 45 kg/ha respectively. PFP of chemical fertilizer N, P2O5, K2 O were 51.52, 135.69 and 158.26 kg/kg respectively. For chemical fertilizer N, P2O5, K2 O, compared with the level of fertilizer rates, 48.0%, 42.4% and 7.2% of households used rational rates respectively, 22.6%, 11.2% and 0.6% of households used excessive rates respectively, while 29.4%, 46.5% and 92.2% of households used insufficient rates respectively. Households using insufficient rates of NPK fertilizers have a potential to increase the rice yields with 77 thousand tons, if using rational rates. We concluded that the households in Qin-Ba mountain area used both excessive and insufficient rates of nitrogen and phosphate fertilizers, but potassium fertilizer and organic manure inputs where both generally insufficient.(6) In Qin-Ba mountain area of southern Shaanxi, the average yield of rapeseed was 2355 kg/ha, and the ratio of households of getting the yield up to medium level was 60.7%. The rates of total N, P2O5 and K2 O were 179, 80 and 54 kg/ha respectively, meanwhile the rates of chemical fertilizer N, P2O5 and K2 O were 145, 62 and 34 kg/ha respectively. The yield of rapeseed had large significant relationship with chemical fertilizer N, P2O5, K2 O, which showed diminishing returns trend. For chemical fertilizer N, P2O5, K2 O, compared with the levels of fertilizer rates, 38.5%, 27.6% and 25.9% of households used rational rates respectively; 15.2%, 26.2% and 10.3% of households used excessive rates respectively; while 46.3%, 46.2% and 63.8% of households used insufficient rates respectively. If households who had used insufficient chemical fertilizer NPK rates increased the nutrients rates up to the rational level, the yield of rapeseed could be increased 56100 tons in the whole region. In addition, only 45.3% and 41.7% of households who used organic manure and boron fertilizer on rapeseed respectively. The average yield could be increased 101 kg/ha under the situation of using boron fertilizer. The current situation of household fertilization on rapeseed in the region was that the nitrogen and phosphate fertilizer inputs were both excessive and insufficient, and the potassium fertilizer, boron fertilizer and organic manure inputs were all insufficient.(7) From the 1970 s to the 2000 s in the Loess plateau area of northern Shaanxi, Weibei dry plateau and Guanzhong irrigated area of the Loess Plateau in Shaanxi province, chemical fertilizer NPK inputs and yields of wheat and maize increased at the farmers' level. In the 1970 s, N was deficient on wheat and maize plots in the different regions; thereafter N was in surplus. In the same way, P gradually changed from deficit to surplus levels. However, K deficiencies became more and more severe. In addition, soil organic matter, total nitrogen, alkali-hydrolysis nitrogen, available phosphorus and available potassium increased over the same period. The PFP of N, NP and NPK on wheat and maize all decreased from the 1970 s to the 2000 s as a whole. With the increase in N fertilizer inputs, both soil total nitrogen and alkali-hydrolysis nitrogen increased; P fertilizer increased soil available phosphorus and K fertilizer increased soil available potassium significantly. |
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