长期不同培肥措施下玉米产量稳定性及棕壤氮素累积分布特征

  【目的】  研究长期不同培肥措施下玉米产量的稳定性、可持续性和土壤矿质氮累积分布、微生物量氮含量特征,为制定合理的施肥措施和保证东北棕壤地区农业的可持续绿色发展提供理论依据。  【方法】  棕壤肥料长期定位试验始于1979年。选取其中的12个处理:不施肥对照(CK)、单施氮肥(N)、氮磷肥配施(NP)、氮磷钾肥配施(NPK)、低量有机肥(M1)及其与化肥配施(M1N、M1NP和M1NPK)、高量有机肥(M2)及其与化肥配施(M2N、M2NP和M2NPK),分析长期施肥下玉米产量的变化,并于2018年在玉米收获期采集植株和土壤样品,阐明玉米地上部吸氮量变化,0—100 cm土层土壤矿质氮分布、累积及微生物量氮含量的差异。  【结果】  长期不同施肥下玉米产量呈波动变化,且在1979—1998年内玉米产量变化趋势较平稳,1999—2018年内变幅较大。M1NPK、M2NPK处理玉米平均产量最高,在试验前20年较NPK处理分别提高了10.3%、11.7%,后20年分别提高了17.1%、19.4%。随着试验年限增加,玉米产量的稳定性和可持续性增加,有机肥配施化肥各处理高于单施化肥处理,在试验前20年和后20年玉米产量的可持续性指数(SYI)介于0.43～0.58和0.50～0.67,低量有机肥配施处理高于高量有机肥配施处理。配施有机肥各处理肥料贡献率高于单施化肥处理,且试验后20年M1NPK处理肥料贡献率最高,达54%。施肥40年后(2018年)玉米地上部吸氮量以M1NPK处理最高(302 kg/hm2),与M2NPK处理差异不显著。配施低量有机肥玉米收获期80—100 cm土层土壤矿质氮含量较低,M1NPK处理 0—100 cm土层土壤矿质氮贮量为127 kg/hm2,显著低于M1N和M1NP处理。而高量有机肥配施各处理0—100 cm土层土壤矿质氮贮量较化肥试区和低量有机肥试区分别增加了324.5%和172.9%,增加了氮素损失风险。此外,长期配施有机肥处理0—40 cm土层土壤微生物量氮含量增加,但低量和高量有机肥试区各处理间差异不显著。  【结论】  长期不同培肥措施会影响玉米产量的稳定性和可持续性,改变土壤氮素分布和累积,进而影响玉米氮素吸收。低量有机肥(13.5 t/hm2)配施氮磷钾化肥可促进玉米生长和氮素吸收,降低0—100 cm土层土壤矿质氮贮量,降低氮素损失风险,增加微生物量氮含量,较高的微生物量氮又可作为有机氮库来增加土壤供氮并固持易损失的矿质氮和肥料氮,以保证玉米的高产稳产和环境友好。     

Enhancing phosphorus availability,soil organic carbon,maize productivity and farm profitability through biochar and organic–inorganic fertilizers in an irrigated maize agroecosystem under semi‐arid climate

Biochar amendments offer promising potential to improve soil fertility, soil organic carbon (SOC) and crop yields; however, a limited research has explored these benefits of biochar in the arid and semi‐arid regions. This two‐year field study investigated the effects of Acacia tree biomass‐derived biochar, applied at 0 and 10 t ha^?1 rates with farmyard manure (FYM) or poultry manure (PM) and mineral phosphorus (P) fertilizer combinations (100 kg P ha^‐1), on maize (Zea mays L.) productivity, P use efficiency (PUE) and farm profitability. The application of biochar with organic–inorganic P fertilizers significantly increased soil P and SOC contents than the sole organic or inorganic P fertilizers. Addition of biochar and PM as 100% P source resulted in the highest soil P (104% increase over control) and SOC contents (203% higher than control). However, maize productivity and PUE were significantly higher under balanced P fertilizer (50% organic + 50% mineral fertilizer) with biochar and the increase was 110%, 94% and 170% than 100%‐FYM, 100%‐PM and 100% mineral fertilizer, respectively. Maize productivity and yield correlated significantly positively with soil P and SOC contents These positive effects were possibly due to the ability of biochar to improve soil properties, P availability from organic–inorganic fertilizers and SOC which resulted in higher PUE and maize productivity. Despite the significant positive relationship of PUE with net economic returns, biochar incorporation with PM and mineral fertilizer combination was economically profitable, whereas FYM along biochar was not profitable due to short duration of the field experiments.     

Integrated use of organic and inorganic inputs in wheat-fodder maize cropping sequence to improve crop yields and soil properties

A 2-year field study was conducted to evaluate the effect of two organics, farmyard manure and vermicompost, each at three rates (0, 5, 10 t ha^?1 and 0, 1, 2 t ha^?1, respectively), along with two levels of mineral fertilizer (75% and 100% of recommended dose), on crops yields and soil properties under a wheat–fodder maize cropping sequence. Individual addition of organics at a higher level increased yields of wheat and subsequent maize. Soil microbial biomass carbon was enhanced as both a direct and residual effect with the addition of farmyard manure followed by vermicompost and fertilizer treatments, and also by combined addition of manure with either vermicompost or mineral fertilizer. Farmyard manure increased the availability of soil macro- and micronutrients, whereas vermicompost influenced only the availability of micronutrients at wheat harvest. A residual effect of farmyard manure and mineral fertilizers was found for available N. Meanwhile, the residual status of micronutrients in the soil was either maintained or significantly improved due to organic amendments (Mn and Zn with farmyard manure; Fe and Zn with vermicompost). Interaction of farmyard manure and vermicompost at a higher level benefited the next crop by increasing the yield of fodder maize and improving the availability of P and metals in soil.     

Mineral‐nutrient synergism and dilution responses to nitrogen fertilizer in field‐grown maize

Nitrogen (N)‐fertilizer applications to field‐grown maize may result in a dilution response whereby essential mineral‐element concentrations in shoots would decrease as shoot‐dry‐matter accumulation increased. To investigate this, the effect of N‐fertilizer treatments (no N or fertilizer rate based upon 5.3 or 8.5 t ha^–1 yield goal) on maize (Zea mays L.) shoot dry weight and shoot mineral concentrations (N, P, K, S, Mg, Ca, and Mn) at the sixth leaf (V6), twelfth leaf (V12), and tassel (VT) development stages were investigated in a 2‐year study conducted at Brookings, South Dakota (USA). With increasing N‐fertilizer application rates, shoot dry weight was greater and shoot P and K concentrations decreased. A possible explanation of this dilution response is that planting‐time P and K fertilizers, which were applied in a band near the seed furrow, may have enhanced the uptake of P and K in a manner that was independent of N‐fertilizer treatments. Increased shoot‐dry‐weight production due to the application of N fertilizers, if P and K uptake were similar across N‐fertilizer treatments, would lead to decreased shoot P and K concentrations in N‐sufficient compared with N‐deficient plants. Conversely, N‐fertilizer‐induced increases in shoot dry weight were accompanied by increased shoot concentrations of N, Ca, and Mn. This synergistic response between dry‐weight accumulation and shoot N concentration was present at all leaf developmental stages studied, while that for Ca was present only at VT. Thus, N fertilizer applications that increase shoot dry weight can affect the dilution and synergistic responses of specific mineral nutrients in maize shoots. Crop developmental stage as well as the location of these specific mineral nutrients in the soil profile might play important roles in mediating these responses.     

长期不同施肥条件下土壤微生物量及 土壤酶活性的季节变化特征

研究长期不同施肥条件下褐潮土微生物量碳（SMBC）、微生物量氮（SMBN）和土壤酶活性随季节的变化特征。结果表明,长期施肥条件下土壤SMBC、SMBN含量及土壤酶活性均表现出一定的季节变化。SMBC、SMBN含量在各施肥处理中的顺序为:化肥与猪厩肥配施处理（NPKM）化肥配施玉米秸秆处理（NPKS）单施化肥处理（NPK）不施肥处理（CK）,各处理之间差异显著(P0.05);施肥还显著提高了土壤脲酶、转化酶、碱性磷酸酶活性,有机无机配施的高于单施化肥的。除过氧化氢酶活性随季节变化显著下降外,SMBC、SMBN、酶活性的值一般在夏季（6月到8月）较高。通过双因素单变量方差分析表明,不同施肥制度与季节变化对SMBC、SMBN与酶活性的影响分别达极显著水平（P0.01）,不同施肥制度的SMBC、SMBN与酶活性的季节波动有极显著不同（P0.01）。     

Compaction and rotovation effects on soil pore characteristics of a loamy sand soil with contrasting organic matter content

The high input of mechanical energy in common agricultural practice can negatively affect soil structure. The impact of compaction (P) and rotovation (R) on soil pore characteristics was compared with those in soil from untreated reference (U) plots of a loamy sand soil receiving for 14 yr, either only mineral fertilizer (MF) or, in addition, animal manure (OF). Undisturbed soil cores were taken from two separate fields in consecutive years at an identical stage in the crop rotation. We measured soil organic carbon (OC), soil microbial biomass carbon (BC), and hot‐water extractable carbon (C_hot). Water retention, air permeability and gas diffusivity were determined at ?100 hPa in both years and for a range of water potentials in one of the years. The continued addition of animal manure had increased OC, BC, and C_hot compared with the soil receiving only mineral fertilizer. Soil under treatment OF had larger porosity than that from treatment MF. Treatment P eliminated this difference and significantly reduced the volume of macropores. This interaction between soil organic matter content and mechanical impact was also reflected in the gas diffusion data. Specific air permeability was mainly influenced by mechanical treatment. Modelling the diffusion data normalized to the inter‐aggregate pore space showed no significant treatment effects on pore‐connectivity, although there was a tendency of more water blockage in soil under treatment MF. More studies are needed to confirm this interpretation. Our studies indicate that organic manure increases soil porosity, but compaction reduces the related gas exchange effects to the level of compacted soils receiving mineral fertilizer.     

Soil sulphur status following long-term annual application of animal manure and mineral fertilizers

 In agricultural systems with low S inputs, crops rely on the release of S from organic forms in the soil. In the Askov long-term experiments, started in 1894 on both sandy and loamy soils, soil S status following long-term application of animal manure and mineral fertilizers was investigated in the growing season of 1995. In a field trial with oil-seed rape (Brassica napus, L.) soil analysis, leaf tissue analysis, yield and S removal in plant material was used to characterize differences in availability of soil S. One half of all plots received 63 kg S ha^–1 as gypsum. Long-term fertilization with animal manure or NPK fertilizer increased the content of soil organic C in both soils and of organic S in the sandy soil compared with unfertilized plots. Although dry matter yields were unaffected, the S uptake in harvested crop parts increased considerably after S application. The amounts of N and S in harvested seeds and straw were closely related, but the N : S ratio decreased when S was applied. Soil and plant analyses both indicated that critical levels of S concentrations were reached, and that S application was capable of raising S concentrations well above the critical level. Because no additional mineralization from residual organic S took place, it was concluded that the residual S effect from long-term annual applications of animal manure or mineral fertilizers did not significantly increase the level of soil S available for crops with a short growing season, such as oil-seed rape. Received: 9 January 1998     

长期定位试验中氮肥与磷肥有机肥联合施用通过刺激根的生长增加玉米产量和养分吸收

Imbalanced application of nitrogen (N) and phosphorus (P) fertilizers can result in reduced crop yield, low nutrient use efficiency, and high loss of nutrients and soil nitrate nitrogen (NO₃^--N) accumulation decreases when N is applied with P and/or manure; however, the effect of applications of N with P and/or manure on root growth and distribution in the soil profile is not fully understood. The aim of this study was to investigate the combined effects of different N and P fertilizer application rates with or without manure on maize (Zea mays L.) yield, N uptake, root growth, apparent N surplus, Olsen-P concentration, and mineral N (Nmin) accumulation in a fluvo-aquic calcareous soil from a long-term (28-year) experiment. The experiment comprised twelve combinations of chemical N and P fertilizers, either with or without chicken manure, as treatments in four replicates. The yield of maize grain was 82% higher, the N uptake 100% higher, and the Nmin accumulation 39% lower in the treatments with combined N and P in comparison to N fertilizer only. The maize root length density in the 30--60 cm layer was three times greater in the treatments with N and P fertilizers than with N fertilizer only. Manure addition increased maize yield by 50% and N uptake by 43%, and reduced Nmin (mostly NO₃^--N) accumulation in the soil by 46%. The long-term application of manure and P fertilizer resulted in significant increases in soil Olsen-P concentration when no N fertilizer was applied. Manure application reduced the apparent N surplus for all treatments. These results suggest that combined N and P fertilizer applications could enhance maize grain yield and nutrient uptake via stimulating root growth, leading to reduced accumulation of potentially leachable NO₃^--N in soil, and manure application was a practical way to improve degraded soils in China and the rest of the world.     

生物肥料磷的利用效率：生物有效性和组分

Although to date some technologies producing bio-based phosphorus (P) fertilizers have been proposed and implemented, the efficient use of the recovered products is still limited due to legislative constraints and lack of insights in the P release with time and in the corresponding mechanisms. The aim of this work was to evaluate the fertilizer performance in terms of P release and use efficiency of recovered struvite, FePO₄-sludge, digestate, and animal manure as compared to fossil reserve-based mineral triple superphosphate (TSP). First, product physicochemical characteristics and P fractions in the context of European fertilizer legislation were assessed. Next, a controlled greenhouse experiment was set up to evaluate plant reactions as well as changes of P availability in a nutrient-rich sandy soil with high P status and a nutrient-poor Rheinsand soil with low P status. Soil P fractions were determined in the extracts with water, ammonium lactate and CaCl₂, and in soil solution sampled with Rhizon soil moisture samplers. Based on all results, it is worth conducting long-term field trials to evaluate the P release effect of struvite and digestate as compared to animal manure and TSP on different soil types with varying P status. These products showed promise as sustainable substitutes for conventional P fertilizers and could contribute to a more efficient use of P in agriculture. A refined classification of P application standards/recommendations in terms of soil P status, soil texture, and fertilizer characteristics, next to the crop P demand, is recommended. Moreover, the additional use of Rhizon samplers for determination of direct available P, including dissolved organic P, is proposed for better understanding and categorization of different P fertilizers in environmental and fertilizer legislations.     

长期施肥对土壤微生物生物量碳、氮及矿质态氮含量动态变化的影响

利用位于陕西杨凌的17年长期定位试验研究了长期不施肥(CK)、单施化肥(F)、化肥配施有机肥(F+M)和化肥加秸秆还田(F+S)处理对小麦-玉米轮作体系中作物不同生长时期土壤微生物生物量碳、氮(SMBC、SMBN)和矿质态氮含量的影响。结果表明,0—10 cm土层土壤SMBC、SMBN和矿质态氮含量的变化范围分别为264.8~752.2、37.51~14.8和3.83~8.5 mg/kg。不同处理相比,F+M处理中各采样时期(小麦苗期、拔节期、灌浆期及玉米播种期、大喇叭口期、灌浆期和收获后)土壤SMBC和SMBN含量均为最高,分别为不施肥对照的1.382~.65和1.892~.50倍;F+S处理矿质态氮含量最高,SMBC和SMBN也高于F和CK处理,大部分采样时期的差异达显著水平(P0.05);与CK相比,长期单施化肥也使各时期SMBC和SMBN含量提高。在小麦拔节期到灌浆期的旺盛生长阶段各施肥处理土壤SMBN含量均下降,而矿质态氮含量变化不大,处于较低水平;在玉米大喇叭口期到灌浆期的旺盛生长阶段,F+M、F+S和F处理土壤矿质态氮含量显著下降,而SMBN含量均有所升高。表明在土壤矿质态氮含量较高时,作物首先利用矿质态氮,而在土壤矿质态氮含量处于较低水平时,微生物固持的氮素可能会释放出来供作物吸收利用。     

Unbalanced nutrient ratios in pelleted compound recycling fertilizers

The aim of this study was to contribute to the development of pelleted compound recycling fertilizers with favourable handling and spreading characteristics and balanced nutrient ratios by combining nitrogen (N)‐ and phosphorus (P)‐rich waste resources (meat bone meal, fish sludge or food waste) with potassium (K)‐rich bottom wood ash. Pelleted compound recycling fertilizers with good durability and low dusting tendency were produced by roll‐pelleting preheated waste resources at a suitable moisture content. However, the nutrient ratios in the final products were insufficiently balanced, with too low N concentrations relative to P and K to meet crop demands. In a bioassay using barley (Hordeum vulgare ) and a nutrient‐deficient sand/peat mixture, the relative agronomic effectiveness (RAE ) of pelleted compound recycling fertilizers and reference recycling fertilizers was 22–42% of that of mineral compound fertilizer. Growth limitation was due to reduced N availability (mineral fertilizer equivalent ‐ MFE = 35–57%) or reduced P availability (MFE  = 20–115%), with the greatest P fertilizer value obtained for digestate based on dairy manure and fish sludge. Availability of K in bottom wood ash was masked by the experimental soil.     

Early plant height: A defining factor for yields of silage maize with contrasting phosphorus supply

Silage maize (Zea mays L.) is an important crop for forage on Northwestern European dairy cattle farms. We examined the effect of readily available soil phosphorus (P) on early maize growth and linked in-season height growth to final harvest yield using field plots with contrasting P supply in a one-year study embedded in a long-term experiment. Water-extractable P (Pw) was used as a proxy for readily available P in soil. Plant height, dry matter (DM) accumulation, P and nitrogen (N) uptakes were determined eight times from the two-leaf stage until final whole-crop harvest and fitted to logistic growth models. The models revealed that the final yield was significantly related to the time required to reach the maximum rate of height growth (occurring from 330 to 485 accumulated growing degree units, GDU), but not the time required to reach the maximum rate of DM accumulation (occurring from 561 to 649 GDU). Furthermore, plant height at the four-leaf stage and onwards was significantly related to the final harvest yield. Soil Pw linked closely to height growth parameters; higher levels of Pw gave earlier peaks in height growth. For this light sandy loam with a wide gradient in P content, we conclude that suboptimal P supply postpones height growth and reduces final yields. A sufficient P supply links to an early rapid increase in plant height and forms the potential for optimum nutrient uptake and high forage yields. Thus, early-season plant height may serve as a simple morphometric indicator for final yields.     

有机肥替代20%化肥提高黑钙土养分有效性及玉米产量

  【目的】  化肥减量并配施有机肥是减少肥料损失、提高化肥利用率的有效途径。研究在秸秆条带还田下化肥减量配施不同有机肥对东北地区黑钙土速效养分和玉米产量的影响,以实现玉米高效和可持续生产。  【方法】  于2018和2019年,连续两年在农安试验基地黑钙土上进行玉米田间试验。本试验在秸秆条状还田下,共设置4个处理,即当地常量施肥 (T1)、化肥减量20% (T2)、化肥减量20%配施鸡粪2988 kg/hm2 (T3) 和化肥减量20%配施牛粪5098 kg/hm2 (T4),T1、T3和T4处理的总氮投入量相同。在玉米拔节期和收获期,分别测定土壤pH、有机碳和速效氮磷钾含量,在收获期测产。  【结果】  与T1处理相比,T2处理连续两年玉米产量均未显著降低,土壤有机碳和速效氮磷钾含量与常量施肥处理大体接近;T3和T4处理显著增加了土壤有机碳和速效养分含量。其中,T3处理2018年土壤有机碳、碱解氮、速效磷、速效钾含量分别较T1增加了15.20%、12.20%、16.70%、7.75%,2019年分别增加了13.0%、18.5%、34.2%、18.5%。玉米产量连续两年均以T4处理效果最优,2018和2019年分别较T1增产5.6%和20.8%,T3处理的增产幅度分别为3.75%和15.40%。  【结论】  在秸秆条状还田下,化肥减量配施有机肥可以增加土壤中有机碳和速效氮、磷、钾含量,可实现玉米增产增收。在黑钙土上配施鸡粪的效果优于牛粪。     

Effect Of The Sequential Application Of Liquid Organic Manure And Phosphorus On Maize Agronomic Traits And P Uptake In Some Tropical Soils

Improving phosphorus (P) fertility is challenging in tropical soils because of the fixation of P by soil components. The trial investigated the effect of the sequential application of poultry manure extract (tea) and P fertilizer on maize agronomy and P uptake, through screen house and field experiments. Results indicated that poultry manure tea is rich in nutrients but low in P and could be applied with phosphorus fertilizer to enhance P availability and reduce fixation. Application of P before manure tea produced taller maize plant on the field and the highest P uptake in the screen house and on the field. Manure tea also increased maize dry matter and grain yield. Combined application of poultry manure tea and P fertilizer had positive complementary and synergistic effects. It was concluded that manure tea enhances P availability and reduces P fixation by soil aluminum (Al) and iron (Fe) oxides irrespective of the sequence of application.     

Soil phosphorus fractions after 111 years of animal manure and fertilizer applications

Accumulated soil P in agricultural soils is a major source of soluble and particulate forms of P entering water resources and degrading water quality. However, few research sites are currently available to evaluate the long-term effects of different cropping systems and fertility practices on soil inorganic and organic P accumulation. The objectives of this study were: (1) to compare the forms and quantity of different inorganic and organic soil P fractions in plots on Sanborn Field, which has been cultivated for 111 years; and (2) to assess the use of standard soil test P extractants for determining changes in soil P dynamics over time. A modified sequential P extraction procedure was used to separate labile and stable inorganic and organic P pools from surface soils collected on Sanborn Field in 1915, 1938, 1962, and 1999 from plots in continuous corn, continuous wheat, continuous timothy, and a corn-wheat-clover rotation amended with either manufactured fertilizers, horse or dairy manure or receiving no fertilization since 1888. Additional samples were collected from a native grass prairie site of a similar soil series to estimate soil characteristics at Sanborn Field before initial cultivation in 1888. Observed accumulation of Bray-1 P among fertilizer and manure treatments was attributed to over-application of P due to unrealistically high yield goals for each cropping system. Long-term cultivation of Sanborn Field increased soil bulk density and lowered soil pH and total organic C compared with native prairie. Fertilization either by addition of manufactured fertilizer or manure significantly increased inorganic resin-P and inorganic NaOH-extractable P. Applications of animal manure also significantly increased most organic P fractions compared with the unfertilized treatment. The native prairie had a larger proportion of total P in organic forms compared with cultivated plots, especially in organic NaOH-extractable P, but no significant decreases in either residual or total P were observed due to cultivation. This study confirms that soil P availability in cropping systems that are amended with predominantly organic P amendments may differ from conventional cropping systems relying on manufactured P fertilizers. However, no direct evidence was found to support the hypothesis that any individual inorganic or organic soil P fraction has a better relationship than conventional soil test P extractants with plant P uptake under contrasting organic and conventional fertility practices.     

Codigested dairy slurry as a phosphorus and nitrogen source for Zea mays L. and Amaranthus cruentus L.

Residues from biogas production contain essential plant nutrients such as nitrogen (N), phosphorus (P), and potassium (K) but also organic matter, and should be recycled in crop production. For efficient re‐use as fertilizers, the availability of nutrients for crops and the effect of the residues on soil fertility need to be evaluated. Focusing on the element P, we compared effects of codigested slurry with dairy slurry, highly soluble mineral NPK fertilizer, and a control without any P supply (NK). Codigested slurry used in this experiment was based on anaerobic digestion of dairy slurry, maize silage, and wheat grain. The fertilizing effects were tested in an 8‐week pot experiment on a sandy and a loamy soil using two crop species (Zea mays L., Amaranthus cruentus L.). The plant P uptake was up to 64% greater in the slurry treatments than in the treatment without P. The effect of codigested slurry on P uptake was comparable to that of dairy slurry and mineral P. Plant N uptake from codigested slurry was lower than that from mineral N (NK, NPK), but tended to be higher than from dairy slurry. The water‐soluble and double lactate–soluble P content of the soil was lower in the slurry treatments than in the mineral‐P treatments and accompanied by higher contents of microbial‐bound P. Differences between both organic fertilizers were detected for dehydrogenase activity which was up to 32% lower in soils fertilized with codigested slurry than it was in soils fertilized with dairy slurry. Our results indicate that codigestion of slurries in biogas plants does not substantially alter their fertilizer value as P and N sources for crops.     

粘土包膜缓释尿素的养分释放特征及其增产效应

以尿素为缓释肥料核心,两种粘土矿物为包膜材料,聚乙烯醇为粘结剂,研制出两种包膜缓释肥料,并探讨了两种包膜肥料在土壤、石英砂等介质条件下的氮素释放特征及形态转化规律,还通过盆栽试验进一步研究了包膜尿素的增产效应。试验结果表明,与普通尿素相比,两种粘土矿物肥料均具有较好的缓释性能,在以石英砂为介质时表现的尤为明显;包膜后的尿素具有较明显的生物增产效应,两种包膜肥料在株高、鲜重、干重等主要产量性状方面与普通尿素均存在显著差异。     

The effect of long-term fertilization with organic or inorganic fertilizers on mycorrhiza-mediated phosphorus uptake in subterranean clover

 A pot experiment was conducted with soil from a long-term (74-year) fertilization field experiment to compare the effects of organic and mineral fertilizers on mycorrhiza formation in clover, and mycorrhiza-mediated plant P uptake. Five treatments were selected from the field experiment representing different forms and levels of P. Mycorrhizal effects on plant growth and P uptake were estimated by comparing plants grown in untreated soil containing indigenous arbuscular mycorrhizal (AM) fungi, with plants grown in pasteurized soil. Short-term versus residual effects of fertilizer/manure were also measured by comparing treatments with or without fertilizers added at the start of the pot experiment. Mycorrhiza formation was greatest in soil that had received no P for 74 years, followed by soil having received 30 or 60 Mg ha^–1 farmyard manure (FYM), and soil having received 25 or 44 kg P ha^–1 in NPK fertilizers. Plant growth and P uptake were severely reduced in the absence of AM fungi for all mineral fertilizer treatments. In contrast, plants growing in soil that had received FYM grew equally well or better when non-mycorrhizal. Recent additions of NK fertilizer and FYM had no effect on mycorrhiza formation, while additions of NPK led to reduced colonization. It thus seems that moderate quantities of FYM have less adverse effects on AM than equivalent amounts of nutrients in NPK fertilizers, a phenomenon that is most likely due to a temporal difference in P availability and its gradual release that balance plant demand. Received: 4 November 1999     

The effects of compost in a rice–wheat cropping system on aggregate size,carbon and nitrogen content of the size–density fraction and chemical composition of soil organic matter,as shown by 13C CP NMR spectroscopy

We investigated whether the long‐term application of compost from agricultural waste improved soil physical structure, fertility and soil organic matter (SOM) storage. In 2006, we began a long‐term field experiment based on a rice–wheat rotation cropping system, having a control without fertilizer (NF) and three treatments: chemical fertilizers (CF), pig manure compost (PMC) and a prilled mixture of PMC and inorganic fertilizers (OICF). Following the harvest of wheat in 2010, the mean‐weight diameter (MWD) of water‐stable aggregates and the concentration of C and N in bulk soil (0–20 cm; <2 mm fraction) were significantly greater (P < 0.05) in PMC and NF plots than in CF or OICF plots. Pig manure compost significantly increased the proportion of >5‐mm aggregates, whereas CF significantly increased the proportion of 0.45‐ to 1‐mm aggregates. The C and N contents of all density fractions were greater in PMC than in other treatments with levels decreasing in the following order: free particulate organic matter (fPOM) >occluded particulate organic matter (oPOM) > mineral‐combined SOM (mineral–SOM). Solid‐state ¹³C CPMAS NMR spectra showed that alkyl C/O‐alkyl C ratios and aromatic component levels of SOM were smaller in PMC and OICF plots than in CF plots, suggesting that SOM in PMC and OICF plots was less degraded than that in CF plots. Nevertheless, yields of wheat in PMC and NF plots were smaller than those in CF and OICF plots, indicating that conditions for producing large grain yields did not maintain soil fertility.     

Long‐Term Integrated Nutrient Management for Rice‐Based Cropping Pattern: Effect on Growth,Yield, Nutrient Uptake,Nutrient Balance Sheet,and Soil Fertility

Abstract

A 7‐year‐long field trial was conducted on integrated nutrient management for a dry season rice (Boro)–green manure (GM)–wet season rice (T. Aman) cropping system at the Bangladesh Rice Research Institute Farm, Gazipur during 1993–1999. Five packages of inorganic fertilizers, cow dung (CD), and GM dhaincha (Sesbania aculeata) were evaluated for immediate and residual effect on crop productivity, nutrient uptake, soil‐nutrient balance sheet, and soil‐fertility status. Plant height, active tiller production, and grain and straw yields were significantly increased as a result of the application of inorganic fertilizer and organic manure. Usually, the soil‐test‐based (STB) fertilizer doses for a high‐yield goal produced the highest grain yield of 6.39 t ha^?1 (average of 7 years) in Boro rice. Application of CD at the rate of 5 t ha^?1 (oven‐dry basis) once a year at the time of Boro transplanting supplemented 50% of the fertilizer nutrients other than nitrogen (N) in the subsequent crop of the cropping pattern. A positive effect of GM on the yield of T. Aman rice was observed. Following GM, the application of reduced doses of phosphorus (P), potassium (K), sulfur (S), and zinc (Zn) to the second crop (T. Aman) did not reduce yield, indicating the beneficial residual effect of fertilizer applied to the first crop (Boro rice) of the cropping pattern. The comparable yield of T. Aman was also observed with reduced fertilizer dose in CD‐treated plots. The total P, K, and S uptake (kg/ha/yr) in the unfertilized plot under an irrigated rice system gradually decreased over the years. The partial nutrient balance in the unfertilized plot (T₁) was negative for all the nutrients. In the fertilized plots, there was an apparent positive balance of P, S, and Zn but a negative balance of N and K. This study showed that the addition of organic manure (CD, dhaincha) gave more positive balances. In the T_4c treatment at 0–15 cm, the application of chemical fertilizers along with the organic manures increased soil organic carbon by (C) 0.71%. The highest concentration of total N was observed with T_4c followed by T_4d and T_4b, where CD was applied in Boro season and dhaincha GM was incorporated in T. Aman season. The sixfold increase in soil‐available P in T_4b‐, T_4c‐, T_4a‐treated plots was due to the addition of CD. Dhaincha GM with the combination of chemical fertilizer helps to mobilize soil‐available P by 3 to 6 ppm. The highest amount of soil‐available S was found in T_4c‐ and T_4a‐treated plots. It was 2.5 times higher than that of the initial soil. The application of CD and dhaincha GM along with chemical fertilizers not only increased organic C, total N, available P, and available S but also increased exchangeable K, available Zn, available iron (Fe), and available manganese (Mn) in soil.