Effects of Long-term Located Fertilization on Wheat Yield and Soil Nutrients of Three Types of Soils in Shandong Province

[Objective] This study aimed to investigate the effects of long-term differ- ent fertilization in three types of soils on wheat yield and soil nutrient variation in Shandong Province. [Method] A 30-year located experiment in Jinan of Shandong Province was selected and the results of soil nutrient and crop yield in 1984, 1987, 1988, 1989, 1990, 2001, 2005, 2006, 2007 and 2010 were measured and collected. In this study, five treatments： CK, NP, NK, PK and NPK of the located experiment were selected. [Result] The three types of soils in wheat yields decreased signifi- cantly in the first several years and in 2006. Wheat yields of the treatments with P fertilizers were obviously higher than those without P fertilizers; it was shown that phosphorus is the primary nutritional factor for high-yielding of wheat. The highest yield is from cinnamon soil, followed by that from brown soil, and the lowest pro- duction is from fluvo-aquic soil. Under the same fertilization, the influence of other factors on wheat yield of brown soil is the smallest, while cinnamon soil is vulnera- ble to the influence of external conditions, resulting in larger fluctuation of annual wheat yield. The alkali-hydro nitrogen contents of three kinds of soils first de- creased, then raised, and at last reduced apparently. Since 2007, the change of al- kali-hydro nitrogen content appeared rebounded. The available P contents of no- phosphorus treatments decreased over time while those of the treatments with P fertilizers increased at first, then decreased, and after that kept relatively stable. The available K contents of no K treatments decreased slowly. The treatments of PK and NK had higher available K content than NPK treatment. [Conclusion] Thus, it is an effective fertilization measure to improve the wheat yield by supplying reasonable phosphate fertilizer and nitrogen fertilizer and making up potassium fertilizer.

Effects of Long-term Located Fertilization on the Contents and Composition of Organic Matter in Paddy Soil

To reveal variation of organic matter content in red paddy soil, Through a 27 years-located fertilization experiment in red paddy soil, the content and composi- tion of organic matter in paddy soil were studied in this paper. The result showed that： the dynamics of soil organic matter of the different fertilization treatments showed significant differences, in the premise of equal nutrient （nitrogen and phos- phorus and potassium）, combining application of organic-inorganic was benefited for the accumulation of organic matter in paddy soil than without fertilizer treatment or chemical fertilizer treatment; the dynamics of soil humic acid, HA and FA of chemi- cal fertilizer only and Combining application of organic-inorganic treatments had basi- cally the same trend, But the contents of humic acid, HA and FA of combining ap- plication of organic-inorganic treatments had been higher than that without fertilizer and chemical fertilizer treatment. Moreover combining application of organic-inorganic treatments was benefited for improving the contents of HA and FA, but decreasing HA/FA ratio as an extension of time. Combining application of organic-inorganic was benefited for improving the contents ol readily oxidizable organic matter. And the contents of soil organic matter in long-term experiment and the contents of readily oxidizable O.M were highly significant positive correlation and the contents of soil total nitrogen, avail nitrogen and potassium were significant positive correlation; the contents of soil readily oxidizable O.M and the contents of soil total nitrogen, avail- able P and rice yield were significant positive correlation. Thereinto, the correlation （r=0.818 1 ） between the rice yield and soil readily oxidizable O.M was higher than the correlation （r=0.802 0） between the rice yield and soil organic matter. It showed the soil readily oxidized organic matter had greater contribution to the rice yield.

Crop yields and soil organic carbon dynamics in a long-term fertilization experiment in an extremely arid region of northern Xinjiang, China

A long-term fertilization experiment was set up in northern Xinjiang, China to evaluate the dynamics of crop production and soil organic carbon （SOC） from 1990 to 2012 with seven fertilization treatments. The seven treatments included an unfertilized control （CK） and six different combinations of phosphorus （P）, potassium （K）, nitrogen （N）, straw （S） and animal manure （M）. The balanced fertilization treatments had significantly （P〈0.05） higher average yields than the unbalanced ones. The treatment with 2/3 N from potassium sulfate （NPK） and 1/3 N from farmyard manure （NPKM） had a higher average yield than the other treatments. The average yields （over the 23 years） in the treatments of NPK, and urea, calcium superphosphate （NP） did not differ significantly （P〉0.05） but were higher than that in the treatment with urea and potassium sulfate （NK; P〈0.05）. The results also show that the highest increases in SOC （P〈0.05） occurred in NPKM with a potential increase of 1.2 t C/（hm2.a）. The increase in SOC was only 0.31, 0.30 and 0.12 t C/（hm2.a） for NPKS （9/10 N from NPK and 1/10 N from straw）, NPK and NP, respectively; and the SOC in the NP, NK and CK treatments were approaching equilibrium and so did not rise or fall significantly over the 23-year experiment. A complete NPK plus manure fertilization program is recommended for this extremely arid region to maximize both yields and carbon sequestration.

Effects of Long-term Located Fertilization on Evolution of Available Phosphorus and Phosphorus Pool in Shandong Fluvo-aquic Soil

This study was conducted to investigate the effects of long-term located fertilization on soil phosphorus,the changes of soil available phosphorus(OlsenP),the evolution of soil total phosphorus(TP)and the ratio change of Olsen-P to TP(PAC)by 33-year fertilization experiments in winter wheat-summer maize rotation system in Shandong fluvo-aquic soil.Eight treatments were designed as no fertilization(CK),nitrogen fertilizer(N),nitrogen and phosphate fertilizer(NP),nitrogen and potassium fertilizer(NK),phosphate and potassium fertilizer(PK),nitrogen-phosphate-potassium fertilizer(NPK),reduced NPK fertilizer(N(15)PK),and increased NPK fertilizer(N_(25)PK).Meanwhile,eight organic fertilizer-added treatments were designed based on the application of inorganic fertilizer the same as the above ones.The results showed that TP,Olsen-P and PAC of treatments added with organic fertilizer were higher than those without organic fertilizer,and those of the treatments applied with phosphate fertilizer were higher than those of no phosphate fertilizer.With the increase of years,soil P pool decreased due to crop absorption,nutrient loss and morphological transformation and other causes under the treatments of without and only phosphate fertilizer,while remained stable under the treatments added with organic fertilizer.The PAC values were generally lower in fluvo-aquic soil,and it could be improved by the application of organic fertilizer.On the whole,the application of chemical phosphate fertilizer combined with organic fertilizer could improve the phosphorus content in soil and ensure the supply of phosphorus nutrition.This study would provide scientific basis for fertilization management and soil fertility in fluvo-aquic soil.

Effects of Long-term Located Fertilization on the Physico-chemical Property of Soil Humus

A systematic study concerning the effects of a long-term stationary fertilization on content and property of soil humus in fluvo-aquic soil sampled from Malan Farm, Xinji City, Hebei, and arid red soil and paddy red soil sampled from the Institute of Red Soil, Jinxian County, Jiangxi was conducted. The results showed that long-term fertilization had effects not only on the content and composition of soil humus, but also on the physico-chemical property of humus. With applying organic manure or combined application of organic manure and chemical fertilizer, E4 and E6 values of humic acid decreased in fluvo-aquic soil and arid red soil, but increased in paddy red soil. In paddy red soil, E4 and E6 values of humic acid increased also with a single application of chemical fertilizer, but E4 and E6 values had less change of humic acid in fluvo-aquic soil and arid red soil. The effects on the visible spectroscopic property of f ulvic acid were different from that of humic acid. Long-term application of organic manure or combined application of organic manure and chemical fertilizer could increase E4 and E6 values of f ulvic acid in three types of soil. Single application of chemical fertilizer had less effect on the E4 and E6. Long-term fertilization could also influence the ultraviolet spectroscopic property of humus. With a single application of organic manure or combined application of organic manure and chemical fertilizer, the ultraviolet absorbance of humic acid and f ulvic acid increased in the three types of soil. But this effect was obvious only in short wave length, and the effect could decrease if the wave length increased. With a single application of chemical fertilizer the ultraviolet absorbance of fulvic acid could increase, but it of humic acid increased only in fluvo-aquic soil. Long-term application of organic manure or combined application of organic manure and chemical fertilizer could increase the content of total acidic groups, carboxy groups and phenolic hydroxy groups of humic acid and fuvic acid in the three types of soil. Single application of chemical fertilizer had less effect on the content of total acidic groups, carboxy groups and phenolic hydroxy groups of humic acid and fuvic acid in the three types of soil.

Effects of Long-term Fertilization on Fertility of Lateritic Red Loam Paddy

The change rules of the fertility of red soil paddy under the long-term different fertilization were investigated, and the reasonable fertilization mode to improve the fertility of red soil paddy was discussed. There were eight treatments in the experiment, which were CK （no fertilizer）, N1 （N of 60 kg/hm2）, N2 （N of 120 kg/hm2）, N1P1 （P2O5 of 30 kg/hm2）, N2P1 and N2P2 （P2O5 of 60 kg/hm2）, N2P2K1 （K2O of 45 kg/hm2） and N2P2K2 （K2O of 90 kg/hm2）. All treatments were applied with composted cow dung as the base fertilizer, and each season 50% of the straws were returned to the field. The content of organic matter, nitrogen, phosphorous and potassium in red soil paddy was observed continuously for ten years and their correlation was also analyzed. Under cow manure and straw return to field, organic matter content of different treatments was positively correlated to year. After ten years, organic matter content of surface soil rose by 2.5 g/kg averagely with an annual increase of 0.25 g/kg. Total nitrogen content and organic matter content of different treatments presented similar variation trend. Total nitrogen content rose by 0.35 g/kg averagely with an annual increase of 0.035 g/kg. Among all the treatments, N2P2K1 and N2P2K2 showed the biggest increase, which went up by 0.052 and 0.48 g/kg, respectively. Phosphorous-free treatments （CK, N1, N2） had steady phosphorous content with irregular changes of different years. Total phosphorous content of phosphorous treatments increased year by year. Total phosphorous content of N1P1 and N2P1 rose by 0.008 g/kg every year. The increment range of total phosphorous content of N2P2, N2P2K1 and N2P2K2 was 0.012 -0.013 g/kg annually. Available phosphorous content varied vastly among different treatments. Available phosphorous content of organic fertilizer treatments basically remained stable with irregular changes of different years. Available phosphorous content of organic fertilizer with phosphate fertilizer treatments rose year by year. Available phosphorous content of N1P1 and N2P1 rose approximately by 0.8 mg/kg. Available phosphorous content of N2P2, N2P2K1 and N2P2K2 rose approximately by 1.4 -1.6 mg/kg annually. Potassium fertilizer amount greatly affected total potassium content. Total potassium content of no-potassium treatments （CK, N1, N2, N1P1, N2P1 and N2P2） remained the same. Total potassium content of N2P2K markedly increased year by year, which was 0.014 g/kg annually. Rapid available potassium content of no-potassium treatments （CK, N1, N2, N1P1, N2P1 and N2P2） showed a decreasing trend. With phosphate fertilizer, rapid available potassium content of N2P2K1 and N2P2K2 remained the same or increased year by year. The change trend of slow available potassium content and rapid available potassium content resembled. Rational allocation of organic fertilizer, nitrogenous fertilizer, phosphate fertilizer and potassium fertilizer can significantly improve soil fertility and economic benefits. Balanced fertilization is an effective measure for soil fertility improvement as it＇s shown that nutrients of surface soil accumulate annually.

Changes of Organic Matter, N, P and K Content of Soils in Red Soil Areas Under Long-Term Experiment

The content of organic matter （OM）, nitrogen （N）, phosphorus （P）, and potassium （K） in the three selected soils, including Calcaric Purpli-Orthic Primosols （purple sand-shale parent material）, Dystric Turbi-Anthric Primosols （quaternary red clay parent material） and Typic Udi-Sandic Primosols （granite parent material） were studied under a long-term experiment by using crop straw and inorganic fertilizers at the Hunan Red Soil Experiment Station of Chinese Academy of Agricultural Sciences. The results showed that the contents of OM, N, P and K in the three selected soils increased after 23 years application of crop straw and inorganic fertilizers, but the contents increased much less when crop straw or inorganic fertilizers was applied alone. The nutrient contents in the three soils developed from granite changed more remarkably than those in the soil derived from quaternary red clay and purple sand-shale. It was also found that the contents of OM, N, and P increased slightly in the treatments without applying fertilizers or returning the crop straw to the root bed. Combined application of inorganic fertilizers and crop straw could remarkably increase the contents of OM, alkalihydrolyzable N and available K, the positive correlation between application of organic fertilizers and increase of OM in soil did not always happened, it provided evidence for the relation between appropriate C/N ratio and accumulation of OM in soil. The increase of nutrient content was influenced by the soil properties. By comparing the contents of nutrient in 0-20 cm depth in the three different soils, it was concluded that the most increases of OM, alkali-hydrolyzable N, and available P were observed in Typic Udi-Sandic Primosols with the average increase by 3.03, 27.38, and 21.73 mg kg^-1, respectively. The available K increased in Dystric Turbi-Anthric Primosols with the average increase by 25.82 mg kg^-1, while it decreased in Calcaric Purpli-Orthic Primosols and Typic Udi-Sandic Primosols. It was concluded that the application of inorganic fertilizer and crop straw was important to improve the soil fertility for all of three selected soils. The straw return to the field had played a significant role for enhancement of the soil quality in the study areas. The application of inorganic fertilizer combined with the straw return to the fields could remarkably improve the soil fertility.

Effects of long-term fertilization on soil gross N transformation rates and their implications

Application of fertilizer has been found to significantly affect soil N cycling. However, a comprehensive understanding of the effects of long-term fertilization on soil gross N transformation rates is still lacking. We compiled data of observations from 10 long-term fertilization experiments and conducted a meta-analysis of the effects of long-term fertilization on soil gross N transformation rates. The results showed that if chemical fertilizers of N, P and K were applied in balance, soil p H decreased very slightly. There was a significantly positive effect of long-term fertilization, either chemical or organic fertilizers or their combinations, on gross N mineralization rate compared to the control treatment（the mean effect size ranged from 1.21 to 1.25 at 95% confidence intervals（CI） with a mean of 1.23）, mainly due to the increasing soil total N content. The long-term application of organic fertilizer alone and combining organic and chemical fertilizer could increase the mineralization-immobilization turnover, thus enhance available N for plant while reduce N losses potential compared to the control treatment. However, long-term chemical fertilizer application did not significantly affect the gross NH4＋ immobilization rate, but accelerated gross nitrification rate（1.19; 95% CI： 1.08 to 1.31）. Thus, long-term chemical fertilizer alone would probably induce higher N losses potential through NO3– leaching and runoff than organic fertilizer application compared to the control treatment. Therefore, in the view of the effects of long-term fertilization on gross N transformation rates, it also supports that organic fertilizer alone or combination of organic and chemical fertilizer could not only improve crop yield, but also increase soil fertility and reduce the N losses potential.

Effect of long-term fertilization on soil nitrate distribution

A thirteen years long-term field fertilizer experiment was conducted to monitor the effect of different fertilization on soil nitrate distribution. The results showed: (1) Applying relative excessive N fertilizer could result large quantities of NO3- residue and NO3- movement downward in soil profiles; amending phosphate fertilizer or organic manure with nitrogen fertilizer together could significantly improve the status of NO3- leaching downward due to the balanced uptake of nutrients by crops. ( 2) Appropriate amounts of nitrogen fertilizer which was equal or smaller than the optimal fertilization rate could not result in more NO3- leaching in Northern China. (3) Precipitation influenced the amounts and depth of soil NO3- leaching: NO3- could move to 80 cm depth or below at autumn or at the next spring when rainfall was higher during the rainy season through July to September in North China.

Effects of Long-Term Fertilization on Distribution of Organic Matters and Nitrogen in Cinnamon Soil Macro-Aggregates

Soil samples collected from a 25-year long-term fertilizer experiment carried out on the Earth-cumulic-Orthic Anthrosols in semi-humid farmland ecological system, were used to study the distribution of soil organic matters, total nitrogen, nitrate nitrogen, and ammoniate nitrogen in different grades of soil macro-aggregates in order to study the effects of long-term application of organic manures in combination with chemical fertilizers. It is showed that the percentage of mass of the soil macro-aggregates with long-term application of fertilizers with sizes of 5-2 mm is increased compared with that of the samples with no fertilizer. It is easier to form lager size soil macro-aggregates by the long-term application of organic manures in combination with chemical fertilizers. The contents of organic matters, total nitrogen and nitrate nitrogen are all higher after treatments with different combinations of fertilizers, while there is a little effect on the contents of ammoniate nitrogen. The contents of organic matters, total nitrogen in the grades of soil macro-aggregates from the plough layers of the treated farmland exhibited significant difference. Moreover, the contents of organic matters and total nitrogen in the soil macro-aggregates with the size of 1-0.25 mm is the highest in all treated soil samples. The contents of nitrate nitrogen in soil macro-aggregates increased with the increasing of soil macro-aggregate size except those applied with chemical fertilizer and lower amount of corn stover. The results of correlation analysis revealed that there exists a significantly positive correlation between the percentage of mass of soil macro-aggregates with the size of 5-2 mm and the contents of organic matters, total nitrogen and nitrate nitrogen in the soil samples. However, the correlation between the percentage of mass of soil macro-aggregates with the size of 1-0.25 rnm and the contents of total nitrogen and nitrate nitrogen is significantly negative.The study showed that the highest contributing rates of macro-aggregates fractions to soil fertility is from the soil macro-aggregates fraction with the size of 1-0.25 mm in most of the cases.

Effects of Long-Term Combined Application of Organic and Mineral Fertilizers on Microbial Biomass,Soil Enzyme Activities and Soil Fertility

Soil health is important for the sustainable development of terrestrial ecosystem. In this paper, we studied the relationship between soil quality and soil microbial properties such as soil microbial biomass and soil enzyme activities in order to illustrate the function of soil microbial properties as bio-indicators of soil health. In this study, microbial biomass C and N contents （Cmic ＆ Nmic）, soil enzyme activities, and soil fertility with different fertilizer regimes were carried out based on a 15-year long-term fertilizer experiment in Drab Fluvo-aquic soil in Changping County, Beijing, China. At this site, 7 different treatments were established in 1991. They were in a wheat-maize rotation receiving either no fertilizer （CK）, mineral fertilizers （NPK）, mineral fertilizers with wheat straw incorporated （NPKW）, mineral fertilizers with incremental wheat straw incorporated （NPKW＋）, mineral fertilizers plus swine manure （NPKM）, mineral fertilizers plus incremental swine manure （NPKM＋） or mineral fertilizers with maize straw incorporated （NPKS）. In different fertilization treatments Cmic changed from 96.49 to 500.12 mg kg^-1, and Nmic changed from 35.89 to 101.82 mg kg^-1. Compared with CK, the other treatments increased Cmic ＆ Nmic, Cmic/Corg （organic C） ratios, Cmic/Nmic, urease activity, soil organic matter （SOM）, soil total nitrogen （STN）, and soil total phosphorus （STP）. All these properties in treatment with fertilizers input NPKM＋ were the highest. Meantime, long-term combined application of mineral fertilizers with organic manure or crop straw could significantly decrease the soil pH in Fluvo-aquic soil （the pH around 8.00 in this experimental soil）. Some of soil microbial properties （Cmic/Nmic, urease activity） were positively correlated with soil nutrients. Cmic/Nmic was significantly correlated with SOM and STN contents. The correlation between catalase activity and soil nutrients was not significant. In addition, except of catalase activity, the soil pH in this experiment was negatively correlated with soil microbial properties. In conclusion, soil microbial properties reflect changes of soil quality and thus can be used as bio-indicators of soil health.

Effect of Fertilization on the Impact of Weather Changes on Crop Yield

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Changes in cropland topsoil organic carbon with different fertilizations under long-term agro-ecosystem experiments across China's Mainland

Topsoil soil organic carbon(SOC) data were collected from long-term Chinese agro-ecosystem experiments presented in 76 reports with measurements over 1977 and 2006.The data set comprised 481 observations(135 rice paddies and 346 dry croplands) of SOC under different fertilization schemes at 70 experimental sites(28 rice paddies and 42 dry croplands).The data set covered 16 dominant soil types found in croplands across 23 provinces of China's Mainland.The fertilization schemes were grouped into six categories:N(inorganic nitrogen fertilizer only),NP(compound inorganic nitrogen and phosphorus fertilizers),NPK(compound inorganic nitrogen,phosphorus and potassium fertilizers),O(organic fertilizers only),OF(combined inorganic/organic fertilization) and Others(other unbalanced fertilizations such as P only,K only,P plus K and N plus K).Relative change in SOC content was analyzed,and rice paddies and dry croplands soils were compared.There was an overall temporal increase in topsoil SOC content,and relative annual change(RAC,g kg-1 yr-1) ranged -0.14-0.60(0.13 on average) for dry cropland soils and -0.12-0.70(0.19 on average) for rice paddies.SOC content increase was higher in rice paddies than in dry croplands.SOC increased across experimental sites,but was higher under organic fertilization and combined organic/inorganic fertilizations than chemical fertilizations.SOC increase was higher under balanced chemical fertilizations with compound N,P and K fertilizers than unbalanced fertilizations such as N only,N plus P,and N plus K.The effects of specific rational fertilizations on SOC increase persisted for 15 years in dry croplands and 20 years in rice paddies,although RAC values decreased generally as the experiment duration increased.Therefore,the extension of rational fertilization in China's croplands may offer a technical option to enhance C sequestration potential and to sustain long-term crop productivity.

31年长期施肥对潮土中微量元素演变及小麦微量元素吸收的影响

【目的】在华北平原典型潮土区,研究长期不同施肥措施对土壤全量与有效态铁、锰、锌、铜含量,以及小麦微量元素吸收的影响,为实现农田地力提升与作物高产优质提供理论依据。【方法】长期定位施肥试验位于河南省郑州市,始于1990年,已连续进行了31年。种植制度为冬小麦-夏玉米轮作。选取不施肥(CK),氮钾化肥(NK),氮磷钾化肥(NPK),氮磷钾化肥+秸秆还田(NPKS),氮磷钾化肥+有机肥(NPKM)5种施肥处理,分析每年土壤样品中全量与有效态铁、锰、锌、铜含量,以及作物秸秆与籽粒中相应微量元素含量。【结果】连续施肥31年后,各施肥处理土壤全量铁、锰含量与试验前无显著差异,全量锌、铜含量较试验前显著增加;NPKM处理土壤全量铁、锰、锌、铜含量均高于其它施肥处理。与CK相比,NPKM、NPKS与NPK处理显著提高了土壤有机质含量与阳离子交换量,降低了土壤pH值,有利于土壤中微量元素向有效态转化。NPKM与NPKS处理下土壤有效态铁、锰、锌含量显著高于其它施肥处理。NPK处理下土壤有效铁含量分别比CK和NK处理提高52%与49%;有效锰含量分别比CK和NK处理提高39%与11%。NPKM、NPKS与NPK处理下小麦地上部铁、锰、锌、铜吸收量与各微量元素收获指数显著高于CK与NK处理。但增产对籽粒中微量元素的稀释效应导致NPK、NPKS与NPKM处理下籽粒微量元素含量显著降低,其中铁、锌含量分别为推荐量下限的71%~74%、60%~63%。【结论】化肥与秸秆或有机肥配施有利于提高土壤微量元素的有效性。土壤全量与有效态微量元素含量的提高可促进小麦对微量元素的吸收,但增产对小麦籽粒中微量元素的稀释效应导致小麦籽粒中的铁、锌含量显著低于推荐量的下限。因此,在培肥潮土地力、提高作物产量的同时,也要考虑优化施肥策略或筛选适宜品种,以提高小麦籽粒中铁、锌含量,消除铁、锌元素缺乏对人体健康的不利影响。

Effect of Long-Term Rice Straw Return on Soil Glomalin, Carbon and Nitrogen

A long-term experiment was conducted to investigate how long-term fertilization and rice straw incorporation into soil affect soil glomalin, C and N. The combined application of chemical fertilizer and straw resulted in a significant increase in both soil easily extractable glomalin (EEG) and total glomalin (TG) concentrations, as compared with application of only chemical fertilizer or no fertilizer application. The EEG and TG concentrations of the NPKS (nitrogen, phosphorus, and potassium fertilizer application + rice straw return) plot were 4.68% and 5.67% higher than those of the CK (unfertilized control) plot, and 9.87% and 6.23% higher than those of the NPK (nitrogen, phosphorus, and potassium fertilizer applied annually) plot, respectively. Application of only chemical fertilizer did not cause a statistically significant change of soil glomalin compared with no fertilizer application. The changes of soil organic C (SOC) and total N (TN) contents demonstrated a similar trend to soil glomalin in these plots. The SOC and TN contents of NPKS plot were 15.01% and 9.18% higher than those of the CK plot, and 8.85% and 14.76% higher than those of the NPK plot, respectively. Rice straw return also enhanced the contents of microbial biomass C (MBC) and microbial biomass N (MBN) in the NPKS plot by 7.76% for MBC and 31.42% for MBN compared with the CK plot, and 12.66% for MBC and 15.07% for MBN compared with the NPK plots, respectively. Application of only chemical fertilizer, however, increased MBN concentration, but decreased MBC concentration in soil.

有机—无机肥配施的增产效应及对土壤肥力影响的定位研究

本文根据１３年的定位研究资料，较系统的阐述了不同量有机肥与氮、磷化肥配合施用，及关中灌区两熟制粮食产量、土壤肥力和养分平衡的影响。初步揭示了关中楼土的基本生产力持续时间较短；土壤的供肥能力是玉米高于小麦。作者认为采用有机肥与氮、磷化肥配施，才是该区粮田持续高产和土壤培肥的有效措施。

长期单施化肥对土壤性状及作物产量的影响

1978～ 1998年在陕西关中地区农田的长期定位试验研究表明 ,长期单施化肥基本上可以维持土壤有机质和NP水平 ;单施化肥与化肥配合有机肥处理的作物产量基本相当 .但是 ,单施化肥处理使土壤腐殖质能量水平降低 ,分子缩合程度和芳构化度增大 ,“老化”作用增强 .

有机无机肥长期配施对水稻产量及干物质生产特性的影响

在21年(1981～2002)长期肥料定位试验的条件下,研究了有机无机肥配施对水稻产量及干物质生产特性的影响,结果表明:不同肥料结构对水稻产量和水稻干物质生产均有显著影响。与长期单施化肥相比,长期有机无机肥配合施用可使水稻产量增加2.69%～11.16%,干物质积累量和群体生长率明显提高(主要在生育后期)。

红外光谱法测定肥料施用26年土壤的腐殖质组分特征

采用红外光谱法探讨了有机肥以及有机肥与化学肥料配合施用26年对棕壤腐殖质及其组分富里酸和胡敏酸的结构变化。结果表明,采用红外光谱仪测定肥料施用对腐殖质及腐殖质组分富里酸和胡敏酸结构的影响是可行的。施肥26年后,不同处理肥料施用后腐殖质具有基本一致的结构;在某些特征峰吸收强度上有不同程度的差异,反映了不同肥料处理对土壤腐殖质的结构单元和官能团数量及组成有明显的影响。不同施肥处理胡敏酸也存在一些差别。红外光谱解析表明,与CK相比,施用有机肥或氮磷钾配合施用后,土壤腐殖质中小分子糖类物质减少,芳族类物质增加。试验结果证实,施用有机肥可明显增加土壤水溶性有机物芳构化程度。利用不同肥料处理腐殖质的红外光谱,可以判断土壤有机质的演变程度。

长期稻草还田对紫色水稻土肥力和生产力的影响

通过8年淹水条件下一季中稻的田间定位试验,研究了长期稻草还田以及稻草与不同化肥配合施用对紫色水稻土生产力和土壤肥力的影响。结果表明,稻草与N、P、K化肥配合施用能维持或提高紫色水稻土的生产力和土壤肥力;水稻获得了持续高产,土壤有机质和全氮含量提高,土壤磷的有效性增加,速效钾与试验前基本平衡。纯化肥处理尤其是N、NP、NK处理水稻产量、土壤氮和钾含量逐年降低,不能维持系统生产力和土壤肥力。稻草还田对翌年水稻具有显著的增产作用,8年平均稻草还田处理比对照增产39 5%,稻草的增产作用还随着稻草还田时间的延长而逐年升高。稻草还田携入的钾与化学钾肥具有相同的营养功效,稻草可替代部分化学钾肥。