Efficiency parameters of nitrogen in hog and cattle manure in the second year following application

The efficiency of nitrogen (N) derived from different manures in the years following application must be determined to optimize use of N and reduce impact on the environment. Five N efficiency parameters that were originally developed for commercial inorganic N fertilizers were selected to measure the manure N efficiency in the second year following application of liquid hog and solid cattle manure in semiarid east‐central Saskatchewan, Canada. The manures were applied at two sites (Dixon and Burr) at four rates covering a range from zero to 912 kg N ha^–1 in 1997. A canola (Brassica napus L.) crop was grown in 1997 followed by a spring wheat (Triticum aestivum L.) in 1998 without fertilization. Tested by the wheat, N utilization efficiency (NUE) was similar between the two manures at either site, but it was higher at Dixon site, where the soil properties were better, than at the Burr site (P < 0.07) with cattle manure. Nitrogen physiological efficiency (NPE) was not affected by either manure source or soil. At the Burr site, N agronomic efficiency (NAE) and N recovery rate (NRR) were all higher with the hog than with the cattle manure (P < 0.08 and P < 0.07, respectively), but N harvest index (NHI) was lower with the hog than with the cattle manure (P < 0.04). The similar trends of the NAE, NRR, and NHI between the hog and cattle manure were also found at the Dixon site. However, the differences in NRR between the hog and cattle manure in the second year was rather small in contrast to the large differences in the year of application. Despite that the wheat crop utilized residual hog and cattle manure N equally efficient in producing grain yield, a higher grain N concentration and a higher NHI with the cattle than with the hog manure revealed different N supply dynamics between the two. Possibly due to the low proportion of ammonium (NH₃)‐N in the total N and the high C : N ratio in the cattle manure, mineralization of cattle manure N provided more available N in the later stage of wheat growth than did the hog manure. The N efficiency parameters were useful tools in understanding the impact of residual manure N on wheat production on the Canadian prairies.     

The effect of nickel supply on bulb yield,urease and glutamine synthetase activity and concentrations of urea,amino acids and nitrogen of urea-fed onion plants

The role of nickel (Ni) on urea metabolism of certain plants has been documented, but little is known regarding the growth and physiological response of onion to Ni nutrition, particularly when urea is used as nitrogen source. In this research study, we investigated the effects of Ni on urea metabolism and growth of two onion cultivars (Allium cepa L., cvs. Dorrcheh and Cebolla Valenciana) supplied with urea as nitrogen source. Three levels of Ni (0, 25, and 50 µM) were used in the form of NiCl₂ or Ni-histidine [Ni(His)₂] complex. Addition of Ni positively affected nitrogen metabolism in onion plants fed with urea and thus was correlated with increase of the bulb yield. Regardless of the plant cultivar and the applied Ni source [NiCl₂ or Ni(His)₂ complex], an increase in urease activity and reduction in bulb urea concentration was observed by Ni nutrition. An increase in hydrolysis of urea and production of NH₄⁺ in the presence of Ni was correlated with higher concentration of the total amino acids (AAs) and nitrogen in onion bulbs. The efficiency of Ni(His)₂ complex in improving Ni uptake and increasing activity of urease and glutamine synthetase, two enzymes involved in urea metabolism, was in general greater than NiCl₂. Accordingly, higher concentration of AAs was measured in the onion plants supplied with Ni(His)₂ complex than those supplied with NiCl₂.     

Yellow melon yield in response to mineral or organic fertilization

Although current recommendations in Brazil suggest the application of mineral and organic fertilizers, there is little information regarding the interaction between them in melon plants. This study aimed to evaluate the effects of mineral and organic fertilization in the plant development, nutritional status, and fruit yield of yellow melon. The following fertilizations were evaluated: mineral fertilization; bovine manure; bovine manure associated with mineral fertilization; poultry litter; and poultry litter associated with mineral fertilization. Bovine manure and poultry litter were applied at rates equivalent to 15 m³ ha^?1 and 5 m³ ha^?1, respectively. Phosphorus and potassium were applied based on the results of the soil analysis and nitrogen based on the expected yield of 20 to 30 t ha^?1 of fruits. Phosphate and organic fertilizers were applied at the time of preparation of the beds, while nitrogen and potassium were supplied daily through irrigation water. Goldex F1 melon hybrid seedlings were used in the experiment. Plants were collected to evaluate the dry matter production at beginning of flowering, beginning of fruiting, fruit growth, and fruit harvest. Leaves were collected at flowering stage to evaluate the nutritional status of plants. Harvest was made when the fruits reached the intense yellow coloration. Organic fertilizers alone and combined to mineral fertilizer did not affect the dry matter yield of leaves, stems, fruits and shoot, the concentrations of macro and micronutrients in melon leaves, the nitrogen accumulation in the plant, and the yield of the yellow melon. The application of bovine manure associated to mineral fertilization showed the lowest values of nitrogen recovery applied. Bovine manure application resulted in increase of nitrogen organic forms in soil.     

有机肥氮替代部分化肥氮对棉花养分吸收、氮素利用和产量的影响

为探讨有机肥氮替代化肥氮在新疆棉花生产中的增产增效作用,在滴灌条件下,采用连续2年定位试验,研究了不施氮(CK)、牛粪堆肥(OM)、农民常规施肥(CF)和不同有机肥氮替代10%(OF1)、20%(OF2)和30%(OF3)的化肥氮时,对棉花氮磷钾养分吸收、氮素利用率及产量的影响。与单施化肥相比,有机肥氮替代部分化肥氮均有利于棉花氮磷钾养分吸收,可提高棉花氮素表观利用率、偏生产力、肥料氮贡献率和农学效率。在有机肥氮替代10%化肥氮的情况下,氮素利用率最高并能提高氮素表观利用率10.5个百分点,棉花产量增加6.8%(P<0.05),而且棉花经济效益与单施化肥相当。有机肥氮替代20%的化肥氮时,棉花产量增加7.9%(P<0.05)。有机肥氮替代30%化肥氮,获得与单施化肥相当的产量,氮素表观利用率仅提高3.4个百分点。综合养分吸收、氮素利用效率、产量及经济效益等方面考虑,有机肥氮替代10%化肥氮是该地区中等肥力棉田增产稳产、氮肥增效的合理施肥方式。     

Phosphorus characterization of manure composts and combined organic fertilizers by a sequential‐fractionation method

Characterization of the forms of phosphorus (P) in organic soil amendments was conducted by sequential P fractionation. More than 60% of total P was inorganic P (P_i). The major P_i forms in the cattle‐manure composts were NaHCO₃‐ and HCl‐extractable P fractions. HCl‐extractable P_i was the predominant P form and a considerable proportion of the total P was present in the HCl‐extractable organic P fraction in the poultry manure composts and combined organic fertilizers.     

Increased total nitrogen content of poultry manure by decreasing water content through composting processes

Microbial mineralization of urea and uric acid in poultry litter can lead to loss of nitrogen (N) content and its value as a fertilizer. To minimize the loss of N in the composting processes, controlling the water content in litters is a key to reduce the mineralization processes of N compounds. The N content of litter may be influenced by diets, hen age and the type of poultry houses used. The objectives of the present study were i) to determine the relationship between the water content and the decomposition rate of uric acid in poultry litter and ii) to investigate the effect of hen age and crude protein (CP) percentages in diets on the N content of poultry litter. A layer feeding trial was conducted in two poultry farms with windowless and open-floor houses. An incubation study of poultry litter was performed under different levels of water content. Our study found that the diet CP percentage (16.5–18%) and the growth stage of laying hens did not have a significant effect on the amount of total N (52–56?g?kg^?1) and uric acid-N (26–31g?kg^?1) in fresh litters. At the 7^th day of litter incubation study, the concentration of uric acid-N was 22 g kg^?1 in litters with a water content of 35%, whereas it further decreased to less than 1.3 g kg^?1 in litters with a water content of 55% and higher levels. The decomposition rate of uric acid-N in litter was 0.3–3.1g?kg^?1?day^?1 in the windowless house and 3.1–7.1g?kg^?1?day^?1 in the open-floor house. Decomposition of uric acid in litters was positively correlated to the litter moisture content that is controlled to be lower in windowless houses (40–50%) than in open-floor houses (55–80%) during the composting period. Our study suggests that the use of windowless houses for layer chicken production is effective for producing poultry manure with a high N content.     

有机肥氮素矿化及影响因素研究进展

本文综述了有机肥氮素矿化和影响因素的研究进展。有机肥氮素矿化的研究方法主要有室内培养法和田间原位培养法。非淋洗通气培养法和原状土柱培养法虽不破坏土壤结构,但可能低估有机氮的矿化潜力;间歇淋洗通气培养法可模拟植物吸收不断移除矿质氮,适合大批样品的快速测定,但可能高估有机氮的矿化潜力。田间原位培养法包括聚乙烯袋培养法、顶盖埋管培养法和离子交换树脂法。聚乙烯袋培养法目前使用最广泛,但具有不透水、破坏土壤结构、矿质氮损失等缺点,顶盖埋管培养法虽可透水且不易被损坏,但可引起矿化氮流失。离子交换树脂芯法在不破坏土壤原状的条件下进行培养,虽费时、费力,但对土壤温度、湿度、通气状况反应灵敏,并可消除矿质氮累积的影响。影响有机肥氮素矿化的因素主要包括有机肥特性、温度、水分、土壤质地、施肥等因素。关于畜禽粪便的种类、熟化程度、C/N比、碳氮化合物组成等影响有机肥的矿化量和矿化动力学特征的研究较多。用有效积温来表示有机肥的矿化与温度之间的关系更为合理。目前,关于水分的影响,主要集中在干湿交替对有机氮矿化的影响;关于土壤质地的影响,主要集中在研究粘粒含量与有机质矿化的关系;关于施肥的影响,则重点研究氮肥、钾肥对有机氮矿化和粘土矿物固定氮的影响。今后,研究重点应放在有机肥矿化与有机氮组分关系、与植物有效性关系、有机肥替代化肥当量和替代率以及室内研究结果如何应用到田间指导合理施肥。     

除氨菌系对牛粪堆肥氮素转化的影响

为了减轻牛粪堆肥过程中NH3释放对环境的污染及氮素损失,在牛粪堆肥时添加除氨菌系,研究其对氮素形态转化的影响。加除氨菌系处理的NH4+-N、NH3较对照分别降低20.47%和61.21%,全氮、NO3--N较对照分别提高11.63%和65.01%,酸解有机氮、氨基酸态氮、酰胺态氮和氨基糖态氮含量分别提高12.42%、11.26%、16.92%和19.51%。表明除氨菌系在牛粪堆肥过程中,能够固定NH4+-N向有机氮各组分转化,减少NH3挥发,具有较好的保氮作用。     

长期不同施肥潮土活性有机氮库组分与酶活性对外源牛粪的响应

【目的】研究不同施肥制度下潮土中活性有机氮库及酶活性对新添加有机物料的响应机制,可深入理解不同施肥制度培肥土壤、提高土壤基础地力的机理。【方法】供试土壤采集于从1986年开始的长期定位试验处理,包括CK (不施肥)、OF (常量有机肥)、CF (常量化肥)、OCF (常量有机无机配施) 4个处理。通过室内恒温培养试验,研究添加等氮量牛粪后长期不同施肥潮土有机氮库组分(微生物量氮、可溶性有机氮和颗粒有机氮)含量及土壤酶(α-葡萄糖苷酶、β-葡萄糖苷酶、β-木糖苷酶、纤维二糖水解酶、磷酸酶、过氧化物酶和酚氧化酶)活性的变化特征。【结果】首先,无论添加牛粪与否,土壤全氮、可溶性有机氮和颗粒有机氮含量均随培养时间呈上升趋势或与初始时期差异不显著;添加牛粪的长期不施肥与施化肥处理土壤微生物量氮含量显著低于相同处理不添加牛粪的土壤微生物量氮含量。其次,培养结束后,添加牛粪增加了长期不同施肥潮土全氮、可溶性有机氮和颗粒有机氮含量,分别提高了5.43%~15.49%、5.83%~69.42%及9.75%~42.29%,却降低了土壤微生物量氮含量16.91%~62.10%。另外,施肥、添加牛粪及其交互作用对土壤酶活性具有显著影响(P <0.05);无论添加牛粪与否,不同施肥处理土壤氧化酶(过氧化物酶和酚氧化酶)活性显著低于不施肥处理,不同施肥处理的土壤水解酶活性却呈现不同的变化趋势。不添加牛粪情况下,长期施肥显著提高了除β-葡萄糖苷酶以外的土壤水解酶活性;其中与长期不施肥处理相比,长期施用化肥土壤β-木糖苷酶和β-纤维素酶分别提高了208.74%和180.75%。添加牛粪情况下长期施用有机肥土壤β-葡萄糖苷酶和β-纤维素酶比不施肥分别提高了201.40%和308.04%;冗余分析(redundancy analysis,RDA)显示,添加与不添加牛粪条件下土壤酶活性的关键环境驱动因子不同,在不添加牛粪时为可溶性有机氮,添加后其关键驱动因子为全氮和可溶性有机氮。【结论】不同施肥制度下土壤微生物量氮、可溶性有机氮、颗粒有机氮与土壤全氮之间呈显著正相关;室内好气培养条件下,添加牛粪显著提高了长期不同施肥潮土的全氮、可溶性有机氮、颗粒有机氮含量,却显著降低了土壤微生物量氮含量;不同施肥制度下土壤酶活性差异显著,牛粪的添加改变了影响长期不同施肥潮土酶活性的关键环境因子。     

Long-term residual effects of feedlot manure application on crop yield and soil surface chemistry

Crop response to manure application may extend beyond the year of application due to residual nutrient availability. A field experiment was conducted to evaluate feedlot manure application (at 0 22.5, 45, 90 and 180 Mg ha^?1) and subsequent residual effects (24-yr) on wheat and sorghum grain yields. Sorghum grain yields increased significantly with manure and nitrogen (N) fertilizer application. However, winter wheat grain yield showed no consistent response to manure and fertilizer application in the 9-yr when manure was applied. Averaged across the subsequent 24 years, residual feedlot manure and annual N fertilizer application significantly increased sorghum and winter wheat grain production. Application of cattle manure did increase soil organic matter content, pH and plant available soil nutrients. Our finding showed that growers could take advantage of the long-term benefits of nutrients supplied from manure application to bolster crop production, improve soil quality and reduce fertilizer input cost.     

施氮量对土壤无机氮分布和微生物量氮含量及小麦产量的影响

在高肥力土壤条件下,研究了施氮量对土壤无机氮分布和微生物量氮含量及小麦产量的影响。结果表明,小麦生长期间,施氮处理0100.cm土层硝态氮积累量显著大于不施氮处理;当施氮量大于150.kg/hm2时,随施氮量增加,0100.cm土层硝态氮积累量显著增加;随小麦生育进程推进,施氮处理上层土壤硝态氮下移趋势明显,至小麦成熟时,施氮1952～85.kg/hm2处理60100.cm土层硝态氮含量显著大于其它处理。小麦生长期间,0100.cm土层铵态氮积累量较为稳定,施氮处理间亦无显著差异。与不施氮肥相比,施氮提高小麦生长期间040.cm土层土壤微生物量氮含量;当施氮量小于240.kg/hm2时,随施氮量增加,土壤微生物量氮含量增加。小麦的氮肥利用率随施氮量增加而降低;施氮1051～95.kg/hm2,收获时小麦植株吸氮量、生物产量、子粒产量和子粒蛋白质含量提高;而施氮量大于240.kg/hm2时,小麦生育后期的氮素积累量降低,收获时植株吸氮量、生物产量和子粒蛋白质含量降低。说明本试验条件下,施氮1051～50.kg/hm2可满足当季小麦氮素吸收利用,获得较高的子粒产量和蛋白质含量。继续增加施氮量,土壤微生物量氮含量增加,但土壤中残留大量硝态氮,易淋溶损失。     

Effect of phosphorus‐enriched biochar and poultry manure on growth and mineral composition of lettuce (Lactuca sativa L. cv.) grown in alkaline soil

The use of pyrolysis products of manures gives positive effects on soil fertility, crop productivity and soil carbon sequestration. However, effects depend on soil characteristics, plant species and the raw material from which the biochar is derived, and some negative effects of biochar have been reported. The objective of this study was to evaluate the effectiveness of poultry manure (PM)‐derived biochar on the growth, and P, N, K, Ca, Mg, Fe, Zn, Cu and Mn concentration of lettuce (Lactuca sativa L.) plant. The treatments as follows: control, 20 g/kg poultry manure (PM), 20 g/kg phosphorus‐enriched poultry manure (PM+P), 10 g/kg Biochar (B), 10 g/kg Biochar+P (B+P). Application of biochar and PM significantly increased lettuce growth, and P‐enriched forms of PM and biochar gave the higher growth. PM has no significant effect on the N concentrations but biochar and, P‐enriched PM and biochar treatments significantly increased N concentrations. Phosphorus concentration of the lettuce leaves significantly increased by PM and biochar treatments. Plant K concentrations were also increased by PM and biochar, and their P‐enriched forms. Leaf Ca and Mg concentrations were lower in Biochar and B+P treatments than that of PM and PM+P treatments. Compared to control and PM treatments, biochar applications reduced Fe, Zn, Mn and Cu concentrations of the lettuce plants. The results of this study indicated that application of biochar to alkaline soil is beneficial for crop growth and N, P and K nutrition, but it certainly reduced Fe, Cu, Zn and Mn nutrition of lettuce.     

Effects of combined organic manure and mineral fertilization on soil aggregation and aggregate-associated organic carbon in two agricultural soils

Abstract

The effect of organic manure and inorganic fertilizer on soil aggregate size distribution and stability, and associated carbon (C) within aggregates varies greatly in previous studies because of the differences in soil conditions, cropping systems, and management practices. This study was conducted as two field fertilization experiments, with different cropping systems, under a subtropical climate in China. The two field experiment sites were located in Jinhua (established in April 2011) in the Jinqu basin in Zhejiang province and Jintan (established in October 2010) in the low-middle Yangtze River plain in Jiangsu province. Both experiments consisted of four treatments, including unfertilized (CK), mineral fertilizer nitrogen (N)–phosphorus (P)–potassium (K) (NPK), NPK plus straw (NPK?+?SR), and NPK plus cattle manure (NPK?+?FYM) or half NPK plus cattle manure (1/2NPK?+?FYM). Water stable aggregate size classes (>5, 2–5, 1–2, 0.5–1, 0.25–0.5, and <0.25?mm) and associated soil organic C (SOC) at 0–15?cm depth were measured. The mean weight diameter (MWD), geometric mean diameter (GMD), and water stable aggregates (WSA)?>?0.25?mm were also determined. The results showed that aggregate-size distribution varied with soil types. Combined application of NPK and organic matter (straw residue or cattle manure), unlike the CK and NPK treatments, significantly increased the WSA >0.25?mm, MWD, and GMD, while obviously reducing the proportion of <0.25?mm aggregates. However, no differences in WSA >0.25?mm, MWD, GMD, and associated C were observed between CK and NPK at both sites. The addition of FYM to the NPK treatment yielded the highest SOC contents in bulk soil, and showed significantly higher associations of C within all size aggregates at both sites. In contrast, NPK?+?SR significantly increased SOC within aggregate classes (2–5?mm, 0.5–1?mm, 0.25–0.5?mm, and <0.25?mm) at Jinhua and (>5?mm and 1–2?mm) at Jintan compared to the CK and NPK treatments. Overall, the combined application of FYM and mineral NPK was the best sustainable management practice for the improvement of aggregate stability and SOC sequestration.     

牛粪堆肥过程中有机态氮的动态变化

利用外源微生物进行牛粪高温好氧堆肥试验,研究堆肥过程中不同形态有机态氮组分的变化规律。结果表明,全氮与酸水解氮均呈下降趋势,与不加外源微生物处理相比,外源微生物处理只是加速全氮与酸水解氮含量的降低,并没有引起氮素过多的损失;氨基酸态氮呈现先降低后增加的趋势,堆肥结束时,外源微生物处理含量明显高于不加微生物处理;酰胺态氮与氨基糖态氮各处理含量都在升温期、高温期增加,然后随着堆肥温度的下降而降低,在腐熟期则呈现较平稳的走势。在堆肥的不同时期,外源微生物处理酰胺态氮含量明显低于不加微生物处理,而氨基糖态氮则相反。     

施用钾肥和有机肥对小麦产量、品质的影响

利用布置在河北玉田县的一个钾肥定位试验,研究了在施用氮磷化肥的基础上,施用钾肥和有机肥对小麦子粒产量、17种氨基酸、粗蛋白和粗淀粉含量的影响。结果表明,施用钾肥明显提高了小麦子粒产量,同时提高了天门冬氨酸、蛋氨酸、酪氨酸和赖氨酸的含量;施用有机肥明显提高了蛋氨酸、赖氨酸和脯氨酸的含量;钾肥和有机肥配合施用明显提高了产量、天门冬氨酸、蛋氨酸、酪氨酸和赖氨酸的含量,对上述氨基酸的提高幅度均在10%以上。施用钾肥和(或)有机肥提高了小麦子粒的氨基酸总量、粗蛋白含量,但降低了粗淀粉含量。     

Fertilizer value of nitrogen in hen and broiler manure after application to spring barley using different application timing

The nitrogen (N) fertilizer effect of layer hen and broiler manure applied at different times on spring barley yield was studied in seven Swedish field experiments during 2005–2008. Two experiments had parallel field incubations to study N release after fertilizer application. The effect of total N in manure on N offtake was 30–40% that of mineral N, except in a dry year, when the effect was very low. Although the relative proportions of ammonium N, uric acid N and other N differed between the hen and broiler manure, the effect of total N was similar for both. In field incubations, mineral N decreased from 75 to 60% of total N applied in hen manure, whereas it increased from 20 to 50% in broiler manure, because of net immobilization and release, respectively. The limited fertilizer nitrogen replacement value, corresponding to only 30–40% of total N, could be as a result of ammonia volatilization after rather shallow incorporation with harrow. Net N release from broiler manure lasted for 6–8 weeks after application, after which it generally ceased. In some cases, manure application in early spring gave better yield effects than application at sowing, probably because of better synchronization of the N release with crop N requirements. The residual N effect on the N offtake in crop in the year after manure application was on average 3% of the total N applied, equivalent to a fertilizer replacement value of about 6%.     

华北地区施用有机肥对土壤氮组分及农田氮流失的影响

为研究有机肥施入土壤后引起的土壤氮组分含量变化对农田氮流失的影响,采用小区试验,并结合田间原位模拟降雨试验,分析施用的有机肥中氮组分的量、土壤氮含量、农田氮素流失浓度及流失量三者间的关系。结果表明:有机肥中酸解氨基酸氮、酸解铵态氮含量占全氮比例分别为28.6%～40.6%,21.3%～33.2%,平均为35.4%、26.4%,是有机肥氮的主要组分;随着单位面积施入农田的有机肥中酸解氨基酸氮、酸解铵态氮(均为可矿化氮)的量增加,0～20 cm土层土壤可矿化氮含量也增加,二者呈极显著正相关;随着耕层土壤中可矿化氮含量增加,农田渗漏液中总氮、水溶性总氮、硝态氮浓度增高,二者呈显著或极显著正相关;随着施用有机肥中可矿化氮的量增多,径流液中总氮、水溶性总氮流失量增加,渗漏液中总氮、水溶性总氮、硝态氮浓度及流失量增高,分别呈显著和极显著正相关。因此,农田中高量施入有机肥,可造成土壤可矿化氮含量增加,农田氮素流失风险也随之增大。     

Soil carbon and nitrogen response to 25 annual cattle manure applications

Improving manure management to benefit both agricultural production and the environment requires a thorough understanding of the long‐term effects of applied manure on soil properties. This paper examines the effect of 25 annual solid cattle manure applications on soil organic carbon (OC), total N (TN), and KCl‐extractable NO₃‐N and NH₄‐N under both non‐irrigated and irrigated conditions. After 25 annual manure applications, OC and TN contents increased significantly with the rate of manure application at the top two sampling depths (0–15 cm and 15–30 cm), and the increases were not affected by the irrigation treatment. The NO₃ content increased at all sampling depths with greater increases observed under non‐irrigated conditions, while NH₄ content was not affected by manure application rates or the irrigation treatment. The changes in OC and TN at the surface (0–15 cm) and 15–30 cm depth were dependent on the cumulative weight of manure added over the years. The relationships between cumulative manure OC added and soil OC content and between cumulative manure TN added and soil TN content were linear and not affected by the irrigation treatment. For every ton of manure OC added, soil OC increased by 0.181 g kg^–1 in the topsoil (0–15 cm). Similarly, for every ton of manure TN added, surface soil TN increased by 0.192 g kg^–1. The linear relationship between manure C added and soil C content suggests that the soil had a high capacity for short‐term C sequestration. However, the total amount of NO₃‐N in the soil profile (0–150 cm) was affected by both the manure application rates and the irrigation treatment. A large amount of NO₃ accumulated in the soil, especially under non‐irrigated conditions. The extremely high level of NO₃ in the soil increases the potential risk of surface and groundwater pollution and losses to atmosphere as N₂O.     

长期有机无机肥配施下红壤性稻田水稻产量及土壤有机碳变化特征

利用中国农业科学院红壤实验站红壤稻田长期定位试验,研究了长期有机无机肥配施下双季稻增产潜力和土壤有机碳变化特征。31年的试验结果表明,1）施肥能促进水稻早晚稻稻谷和地上部产量增加,其中,有机肥配施均衡的NPK处理促进作用最大,NPKM处理下稻谷年均产量比NPM、 NKM、 PKM、 M和NPK分别高 5.8%、 10.9%、 16.2%、 15.9%和20.4%。2）施肥能促进水稻土有机碳含量增加,其中,有机肥配施均衡的NPK处理提升效果最为明显, NPKM处理下所测年度土壤有机碳平均含量比NPM、 NKM、 PKM、 M和NPK分别高出2.5%、 3.5%、 2.0%、 0.6%和 32.8%。3）随着试验的进行,单施有机肥对早、 晚稻稻谷和地上部产量的促进效果逐步优于单施化肥氮、 磷、 钾处理（NPK）,对土壤有机碳的提升效果也明显优于单施化肥氮、 磷、 钾。红壤性稻田双季稻生产实践中,有机无机肥配施模式值得推荐,但需均衡配施化肥氮、 磷、 钾。