耕作与施肥措施对江淮地区白土理化性质及水稻产量的影响

针对连续旋耕白土田耕层浅薄、下层土壤黏重紧实、养分分布不均衡等问题,探索适合于白土稻田的耕作与施肥措施,以进一步提高江淮地区白土生产力和水稻产量水平。设置2种耕作方式(旋耕和翻耕)及3种施肥措施(单施化肥、化肥+有机肥、化肥+秸秆还田),通过大田定位试验研究不同耕作方式与施肥措施对白土稻田土壤理化性质、水稳性团聚体分布以及水稻产量的影响。结果表明,相较于旋耕,翻耕降低0—10cm土层土壤养分含量,而使10—20cm土层有机质、全氮、有效磷和速效钾含量分别提高3.2%～8.8%,4.5%～9.2%,5.2%～8.2%和8.3%～17.7%。增施有机肥或秸秆还田使土壤有机质和速效钾含量较单施化肥处理分别提高1.3%～8.6%和4.1%～21.1%。翻耕方式下10—20cm土层土壤容重较旋耕降低14.4%～19.5%,土壤大团聚体比例在0—10,10—20cm土层则较旋耕分别降低3.0%～5.4%和3.5%～9.7%;在翻耕的基础上增施有机肥或秸秆还田土壤容重较单施化肥降低2.1%～6.6%,大团聚体比例则提高2.8%～8.4%。翻耕有利于水稻产量的提高,较旋耕的增产幅度在11.7%～18.0%,增施有机肥或秸秆还田使水稻产量提高1.7%～7.5%。因此,江淮地区连续多年旋耕的白土田进行适宜翻耕结合秸秆还田或增施有机肥可改善0—20cm土层土壤理化性质,有利于水稻产量的提升。     

不同施肥措施对白土腐殖质组成的影响

以白土稻区4年大田定位试验为基础,设置2种翻耕深度(10 cm、20 cm,分别标记为T10、T20)和4种施肥措施(单施化肥、化肥+畜禽粪肥、化肥+秸秆还田、化肥+绿肥,分别标记为F、F+M、F+S、F+G),通过腐殖质组成修改法分别提取表层土壤水溶性物质、胡敏酸、富里酸和胡敏素,研究不同施肥措施对白土腐殖质各组分碳含量的影响。结果表明:单施化肥措施下,翻耕20 cm处理(T20+F)土壤总有机碳和腐殖质各组分碳含量均低于翻耕10 cm处理(T10+F),但差异未达显著水平。在翻耕20 cm的基础上增施有机肥能显著提高土壤总有机碳和腐殖质各组分碳含量,增施畜禽粪(T20+F+M)、秸秆还田(T20+F+S)和增施绿肥(T20+F+G)3处理的土壤总有机碳、胡敏酸、富里酸和水溶性物质碳含量较T20+F处理分别提高14.57%~30.64%、10.36%~30.57%、0.74%~12.31%和14.25%~26.80%。增施有机肥显著提高胡敏素碳含量,T20+F+M、T20+F+S和T20+F+G处理较T20+F处理提高18.87%~35.78%。4年不同翻耕与施肥措施对白土腐殖质性质未产生显著影响。增施有机肥能一定程度上提高土壤PQ值、胡富比、E4/E6值和色调系数。相关性分析表明,胡敏素、胡敏酸、富里酸碳含量与总有机碳含量间均存在显著或极显著正相关,与水溶性物质碳含量间无明显相关性。     

不同培肥措施对河套灌区盐碱地改良效果

为了研究不同培肥措施对盐碱化土壤改良效果,以内蒙古河套灌区盐碱地为对象,通过3年田间试验,研究了等氮素条件下不同培肥措施对土壤pH值、全盐、脱盐率、有机质、全氮、碱解氮、有效磷等指标的影响。结果表明:不同培肥措施土壤剖面盐分变化趋势基本一致,即0～20 cm降低,20～60 cm升高,60～100 cm稳定,其中CK、化肥处理表层土壤(0～20 cm)盐分含量最高,收获期土壤盐分分别为5.33和5.24 g·kg~(-1);秸秆还田、秸秆还田+有机肥、秸秆还田+有机肥+化肥配施处理盐分含量最低,收获期土壤盐分分别为5.0、4.58、4.73 g·kg~(-1)。不同培肥措施0～10、10～20 cm土壤脱盐率分别为7.81%～20.70%、4.48%～16.96%,其中有机肥、秸秆还田与有机肥、秸秆还田+有机肥+化肥配施对促进盐分淋洗、抑制反盐的效果较好,土壤脱盐率分别为11.99%、18.83%、15.65%,以CK和单施化肥处理效果最差,分别为5.74%、6.37%。作物生育期内,不同培肥措施的土壤pH值变化差异不显著,但连续施用有机肥、有机肥+秸秆以及有机肥+秸秆还田+化肥配施耕层土壤pH值较CK处理降幅较大。与CK相比,不同培肥措施均显著提高耕层土壤碱解氮、有效磷的含量(P 0.05),其含量分别提高29.43%～93.14%、17.45%～161.84%;有机肥、有机肥与化肥配施显著提高了土壤有机质和全氮的含量,分别为14.66%、13.36%和13.36%、17.35%。有机肥、秸秆还田、化肥三者配施均能显著提高向日葵产量,其中有机肥+秸秆还田+化肥处理对向日葵产量提高的最为显著,较CK增产44.41%。因此,在等氮素条件下,河套灌区应重视有机肥与化肥、有机肥与秸秆还田、有机肥与秸秆还田+化肥的配合施用,不仅可以培肥土壤、提高脱盐率,还可获得一定的高产。     

秸秆还田对滴灌春小麦产量和土壤肥力的影响

为提高秸秆还田的利用效率,采用大田试验研究了秸秆还田及配肥对小麦产量及土壤理化性状的影响,为干旱区土壤培肥提供科学依据。在常规施肥的基础上设置半量秸秆(S1)、全量秸秆(S2)、有机肥(M)、复混肥(CF)、全量秸秆与有机肥(S2+M)、全量秸秆与复混肥(S2+CF)配施6个处理。结果表明,秸秆配施肥(S2+M)、(S2+CF)对提高小麦的株高、单穗重、穗长和单株穗粒数效果优于单施秸秆处理(S1、S2);秸秆配施肥产量显著高于CK。秸秆配施肥显著降低了0~20 cm和20~40 cm土层土壤容重,提高了0~20 cm土层阳离子交换量,而对20~40 cm影响不显著。秸秆配施肥0~20 cm和20~40 cm土层土壤有机质、全氮、碱解氮、速效磷和速效钾含量均显著高于单施秸秆处理,而单施秸秆处理显著高于单施有机肥和复混肥处理。因此,在施氮、磷肥的基础上全量秸秆还田与有机肥或复混肥配合施用,能更有利于滴灌农田土壤肥力的提升。     

有机物料长期施用对稻田土壤养分的影响

通过2010—2021年连续12年的长期定位试验，研究了紫云英、水稻秸秆、商品有机肥等有机物料还田施用对稻田土壤养分的影响。结果表明：施用有机物料可以有效提高稻田土壤氮磷钾和有机质等含量。与单施化肥处理相比，紫云英还田土壤碱解氮含量增加6.97%，商品有机肥配施土壤有效磷含量增加49.30%，水稻秸秆还田土壤速效钾含量增加49.32%。3种有机物料处理土壤有机质增加相近(6.0%～7.5%)，可以改善土壤酸性但差异不显著。不同有机物料对土壤基础养分的增加差异显著，紫云英还田土壤固氮能力最强，商品有机肥配施土壤磷素增加最明显，秸秆还田土壤钾素提高最显著。可见，有机物料长期还田施用是一种培肥土壤的有效措施，有助于稻田土壤的可持续利用。     

不同培肥措施对新垦耕地红壤肥力和作物产量的影响

在浙江省余杭区瓶窑镇选择2012～2013年开垦建成的红壤农田,设置对照、冬绿肥+秸秆还田、商品有机肥+冬绿肥+秸秆还田和食用菌废渣+冬绿肥+秸秆还田等4种培肥处理,在玉米-番薯旱粮种植模式下,连续进行3年定位试验,探讨了不同培肥措施对新垦耕地红壤肥力和作物产量的影响。田间试验结果表明,对新垦耕地红壤综合培肥效果最好的为冬绿肥+秸秆还田+商品有机肥处理,其土壤有机质、有效磷、全氮及速效钾含量分别比对照增加90.7%、71.1%、71.0%和28.6%,旱粮产量增加22.6%;其次为冬绿肥+秸秆还田+食用菌废渣处理,其土壤容重比对照处理下降了6.7%,土壤有机质、全氮、有效磷和速效钾含量分别比对照增加88.4%、40.3%、39.1%和18.3%,旱粮产量增加21.6%;单纯采用种植冬绿肥和秸秆还田措施对新垦耕地红壤培肥的效果不明显。试验结果也表明,在不施石灰的情况下,以施用有机物质为主的培肥措施可能会导致土壤酸化。据此认为,由于新垦红壤基础地力较差,应采用多种途径增加有机肥料的投入,如在种植冬绿肥和秸秆还田的基础上适当施用养分含量较高的有机肥料可获得更好的作物增产、地力提升效果。     

有机肥氮替代化肥氮和土壤改良剂对盐碱地棉花产量和土壤养分的影响

为探讨有机肥氮替代化肥氮对南疆盐碱地棉花产量及土壤养分状况的影响,在南疆漫灌条件下,设置不施肥(CK)、单施化肥(A)和有机肥氮替代15%(B)、30%(C)和45%(D)的化肥氮处理,对棉花产量和土壤肥力的变化进行了田间试验研究。结果表明,不同有机肥氮替代化肥氮处理中,有机肥氮替代15%化肥氮的增产效果明显,尤其是在秸秆还田加施土壤改良剂条件下,有机肥氮替代15%化肥氮较单施化肥增产15.18%。在秸秆还田条件下,有机肥氮替代45%化肥氮的处理中,土壤有效磷和速效钾含量显著高于其他处理;在加施土壤改良剂条件下,土壤有机质和碱解氮含量显著高于其他处理。有机肥替代化肥使土壤盐分含量下降,下降程度随着土壤剖面深度增加而降低。研究结果表明:有机肥氮替代化肥氮,在保持棉花稳产的同时减少了化肥氮的施     

有机肥和秸秆还田对河套灌区盐渍化土壤养分及微生物数量的影响

为探讨施用有机肥和秸秆还田对盐渍化耕地土壤的培肥效果及改土效应,以河套灌区典型盐渍化土壤为研究对象,对比分析了不施肥(CK)、化肥(CF)、化肥+有机肥(CFM)、化肥+秸秆还田(CFS)对土壤pH、有机碳、全氮含量、速效氮磷钾含量和微生物数量的影响,并通过简单相关分析和冗余分析研究等氮条件下浅层(0～20 cm)土壤化学性质与土壤微生物数量间的相关关系,揭示不同培肥措施下土壤微生物数量差异的驱动因子,明确施用有机肥和秸秆还田这2种主要培肥措施下土壤肥力的变化特征。结果表明:与CK处理相比,CFM和CFS处理的土壤pH分别降低了1.36%～1.78%和1.02%～1.44%,土壤盐渍化得到改善;CFM和CFS处理提高了土壤有机碳和全氮含量,土壤碱解氮、有效磷和速效钾含量也显著增加,且施用有机肥的提升效果优于秸秆还田;在土壤微生物方面,CFM处理可显著提高土壤细菌数量(53.44%～59.78%)和放线菌数量(10.08%～16.79%),CFS处理可显著提高土壤真菌数量(29.99%～49.06%)。综上所述,增施有机肥和秸秆还田可有效降低土壤pH,增加土壤有机碳和速效养分;同时改善了土壤微环境,显著增加了土壤微生物数量。该研究结果可为河套灌区盐渍化土壤的改土培肥提供参考。     

长期施用绿肥对红壤稻田水稻产量和土壤养分的影响

通过对26年长期定位试验结果的统计分析,结果表明:绿肥与化肥长期配合施用有利于水稻稳产增产,减少化肥的使用量,提高化肥NPK养分的农学利用效率达60%以上。26年水稻平均产量以OM3处理(紫云英+猪粪)最高,比CK增产64.47%,比NPK处理增产6.86%;其化肥养分农学效率为16.33kg/kg,比NPK处理化肥养分农学效率高118.9%。绿肥与化肥长期配合施用土壤有机质、全氮和全磷均有所积累,积累的量与肥料施用量及有机肥种类相关,以紫云英+猪粪处理最优。土壤钾素均表现亏缺,土壤全钾和速效钾均低于试验前,亏缺幅度最小的是紫云英+稻草处理,其土壤全钾和速效钾分别比对照高4.28%和13.94%。通过对土壤有机质、全氮、全磷和全钾与水稻产量关性分析,相关系数最高的为土壤全钾(r=0.808**),说明缺钾已成为限制红壤稻田高产的主要肥力因子。     

施肥方式对重度侵蚀黑土养分及玉米产量影响

针对东北地区土壤侵蚀加剧,土壤有机质含量和土壤氮储量偏低,增产潜力下降等问题,采用培肥定位试验研究化肥和有机肥配施对土壤有机质和氮磷钾养分及玉米产量的影响。结果表明,化肥配合适量干牛粪施用对土壤的改良作用,优于化肥配合等养分含量的秸秆粉碎还田。相对不施肥的对照,0²0 cm土层有机质、全氮、碱解氮、有效磷、速效钾都显著增加,差异达到0.05显著水平。有机无机配施对2020 cm土层有机质、全氮、碱解氮、有效磷、速效钾都显著增加,差异达到0.05显著水平。有机无机配施对20⁴0 cm深土壤质量改善作用有限。与单施无机肥处理相比,有机无机肥配合施用可增产14.51%40 cm深土壤质量改善作用有限。与单施无机肥处理相比,有机无机肥配合施用可增产14.51%³3.03%,差异达到0.05显著水平。施入过多的有机肥料会使短时期内土壤有机质及速效养分增加的比率降低,本研究建议针对重度侵蚀黑土(破皮黄黑土)的改良,干牛粪的施用量应为3.75 t hm-2,玉米秸秆的施入量应为当年生产量的50%左右。     

Effect of long-term balanced and imbalanced inorganic fertilizer and FYM application on chemical fraction of DTPA-extractable micronutrients and yields under rice–wheat cropping system in mollisols

The imbalanced use of chemical fertilizers under intensive cultivation practices over a period of years leads to various soil-associated problems particularly nutrient availability. Thus, to examine the effect of long-term application of balanced and imbalanced inorganic fertilizer and farm yard manure (FYM) application on the chemical fraction of DTPA-extractable micronutrients under rice–wheat cropping system after 29 years, the observations were recorded from the ongoing field experiment at Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, India. An application of balanced inorganic fertilizer with FYM in rice, while without FYM in wheat significantly improved the DTPA-extractable Zn, Fe, Mn and Cu after rice and wheat crops in both the surface and sub-surface soil layers. Lowest DTPA-extractable Zn, Fe, Mn and Cu were recorded, in surface and sub-surface soil under rice and wheat crops in control. The highest DTPA-extractable Zn, in both surface and sub-surface layers of rice (3.31, 1.62 mg kg⁻¹, respectively) and wheat (2.96, 0.99 mg kg⁻¹, respectively) was recorded because of application of N₁₈₀+P₈₀+K₄₀+Zn(F) + FYM in rice and N₁₈₀+P₈₀+K₄₀+Zn(F) in wheat. However, the DTPA-extractable Fe, Mn and Cu were highest in rice and wheat because of N₁₂₀+P₄₀+K₄₀+FYM and N₁₂₀+P₄₀+K₄₀ application, respectively. The balanced use of inorganic fertilizer with FYM (N₁₈₀+P₈₀+K₄₀+Zn(F) + FYM) in rice and without FYM [N₁₈₀+P₈₀+K₄₀+Zn(F)] in wheat supported the highest rice (6.74 t ha⁻¹) and wheat (3.50 t ha⁻¹) grain yields, while lowest in control. Based on the study results, long-term application of FYM at 5 tonnes ha⁻¹ in rice crop sustained the availability of DTPA-extractable cationic micronutrients to rice and wheat in Mollisols.     

Effects of Fertilizers on Yield,Sustainability, and Soil Fertility under Rainfed Pigeon pea + Rice System in Subhumid Oxisol Soils

A long-term field experiment was conducted at the research farm of the All-India Coordinated Research Project for Dryland Agriculture, Phulbani, Orissa, India, from 2001 to 2006 to identify the best integrated nutrient-use treatments for ensuring greater productivity, profitability, sustainability, and improved soil quality in pigeon pea + rice (two rows of pigeon pea followed by five rows of rice alternately) intercropping system. In all, nine treatments, eight comprising integrated nutrient-use practices, chemical fertilizer (CF), farmyard manure (FYM), and green leaf manure (GLM) to supply nitrogen (N) at 45 kg N ha^–1 and one farmer's practice equivalent to 25 kg N ha^–1 (FYM 5 t ha^–1), were tested on a long-term basis. Results of the study revealed that 20 kg N ha^–1 (FYM) + 25 kg N (CF) gave maximum mean rice grain yield of 1.52 t ha^–1, followed by 20 kg N (GLM) + 25 kg N (urea) with grain yield of 1.51 t ha^–1. In the case of pigeon pea, 30 kg N (FYM) +15 kg N (urea) gave maximum pigeon pea grain yield of 0.94 t ha^–1, which was 34% greater than the sole application of chemical fertilizer. Pigeon pea grain yield tended to increase with increasing proportion of organic N in FYM + CF or GLM + CF combinations. Application of 20 kg N (FYM) + 25 kg N (urea) recorded maximum mean rice equivalent yield of 3.59 t ha^–1 and sustainability yield index of 59%. While studying profitability, application of 20 kg N (FYM) + 25 kg N (CF) gave maximum net returns of US$168.94 ha^–1. Impact of treatments on soil quality as assessed in terms of relative soil quality indices (RSQI) increased with increasing proportion of organic sources of N. Using an innovative and new approach, an index of integrated productivity–sustainability–profitability–soil quality performance index (I _P,S,Pr,SQ) was computed to make a precise evaluation of the treatments. Based on this index, the order of performance of the treatments was T₆ [20 N (FYM) + 25 N (CF)] (7.7) > T₇ [30 N (FYM) + 15 N (CF) (6.9)] > T₃ [20 N (GL) + 25 N (CF)] (6.8) > T₅ [10 N (FYM) + 35 N (CF) (6.6)] > T₉ [GL] (6.5) > T₈ [CF] (6.2) > T₄ [30 N (GL) + 15 N (CF)] (6.0) > T₂ [10 N (GL) + 35 N (CF)] (5.7) > T₁ [FYM at 5 t ha^–1] (4.1). Thus, the results and the methodology adopted in this study using long-term data would be very useful to researchers, farmers, land managers, and other stakeholders not only in India but also across the world under similar climatic and edaphic situations.     

Distillery effluents effect on soil organic carbon and aggregate stability of a Vertisol in India

Distillery effluent, a waste by-product of distillery industries, is usually applied to arable land near the distilleries as irrigation water or as a soil amendment. To evaluate the effect of distillery effluent, both spent wash (SW) and post-methanated effluent (PME), on soil organic carbon and aggregate stability, a field experiment on a soybean (Glysine max L.)–wheat (Triticum aestivum L.) system was conducted for five years on a Vertisol of central India. The treatments were control (no fertilizer or manure or SW or PME, T₁), 100% NPK + farmyard manure (FYM) @ 4 Mg ha⁻¹ to soybean (T₂), four graded levels of SW, viz., 2.5 cm SW to soybean and none to wheat (T₃), 2.5 cm SW to soybean and 1.25 cm to wheat (T₄), 5 cm SW to soybean and none to wheat (T₅), 5 cm SW to soybean and 2.5 cm to wheat (T₆), and four graded levels of PME, viz., 2.5 cm PME to soybean and none to wheat (T₇), 2.5 cm PME to soybean and 1.25 cm to wheat (T₈), 5 cm PME to soybean and none to wheat (T₉), 5 cm PME to soybean and 2.5 cm to wheat (T₁₀). The organic carbon of the surface (0–15 cm) soil that received either PME or SW (treatments T₃–T₁₀), was significantly (P < 0.05) higher than in treatments T₁ and T₂. The mean weight diameter (MWD) of water stable aggregates in this soil layer was also significantly higher in treatments T₃–T₁₀, compared with T₁ and T₂. The MWD showed a positive linear relationship with the organic carbon content of the soil (R² = 0.54**). The proportion of macro-aggregates was higher in SW treated plots than PME, no distillery effluents and NPK + FYM treatments. However, the micro-aggregates showed the reverse trend. The macro-aggregate-associated carbon was higher in SW treated plots. It was highest in T₆ and lowest in T₁. The plots receiving the PME and SW showed increased soil organic carbon, MWD, percentage macro- and micro-aggregate-associated carbon than T₁ and T₂. Application of distillery effluents increased the aggregate stability of the Vertisol through enhanced soil organic carbon as well as the aggregate-associated carbon. So application of SW or PME could be a viable option for soil aggregate stability and enhanced productivity.     

连续翻压紫云英对福建单季稻产量与化肥氮素吸收、分配及残留的影响

【目的】紫云英翻压后在一定程度上可改善土壤理化性状,并提高后作水稻的产量,但是该机理是由于紫云英翻压矿化后提供的氮素还是由于与翻压紫云英后化肥氮素利用率的提高有关尚不清楚,因此,本项目通过连续4年紫云英翻压还田的定位试验与原状土柱模拟及15N示踪,研究了福建单季稻区紫云英压青回田对水稻产量与化肥15N吸收、 分配及残留的影响。【方法】采用单季稻田间定位试验,设5个处理: 1）对照,不翻压紫云英,不施化肥（CK）;2）不翻压紫云英,常规化肥施用量（100%H）;3）紫云英＋常规化肥用量（Z+100%H）;4）紫云英＋60%的常规化肥（Z+60%H）;5）只翻压紫云英,不施化肥（Z）。常规化肥用量（100%H）为施氮量N 135 kg/hm2,N∶P2O5∶K2O=1∶0.4∶0.7,每年紫云英翻压量为18000 kg/hm2。每个处理3次重复,小区面积15 m2,种植水稻为每小区2015丛。于定位试验的第4年,在田间定位试验小区中,采用15N-尿素（丰度10%）示踪法与原状土柱模拟水稻植株的氮素吸收及分配情况。PVC管直径25 cm,长35 cm,其中压入田面下20 cm,每小区埋两个土柱,每个土柱中种植两株水稻。【结果】紫云英年翻压18000 kg/hm2并结合施用100%化肥（Z+100%H）,水稻子粒4年平均产量比单施100%化肥（100%H）增产6.5%,同时在18000 kg/hm2 的紫云英翻压量下,主作物水稻化肥减量40%（Z+60%H）的产量与100%H的处理基本相当。Z+100%H处理对提高水稻分蘖期植株氮含量最为明显,尤其是茎叶氮含量较100%H提高7.0%,差异显著。虽然不同施肥处理水稻生育期的化肥氮素利用率无明显变化,但Z+100%H处理分蘖期与成熟期植株氮素吸收量分别较100%H提高23.0%与18.0%,说明绿肥与化肥配施有利于水稻植株吸收外源氮素,且植株吸收氮的差异主要来自于紫云英矿化的氮源。Z+60%H 与100%H处理的分蘖期与成熟期植株氮素吸收量则基本相当。不同施肥处理均有提高土壤全氮含量的趋势;Z+60%H 处理的耕层土壤化肥氮素的残留率最高,并显著高于Z+100%H处理。【结论】连续4年翻压紫云英明显提高了福建单季稻区黄泥田的农田生产力,在减少40%常规化肥用量的情况下仍可维持产量稳定。翻压绿肥减肥增效的主要机制之一是紫云英矿化的养分替代了化肥。     

Soil microbial biomass,crop yields,and bacterial community structure as affected by long-term fertilizer treatments under wheat-rice cropping

Soil microbial biomass carbon (SMBC) and nitrogen (SMBN), soil microbial community structure, and crop yields were studied in a long-term (1982–2004) fertilization experiment carried out in Suining, Sichuan province of PR China. Eight treatments included three chemical fertilizer (CF) treatments (N, NP, NPK), three CF + farmyard manure (M) treatments (NM, NPM, NPKM), M alone and no fertilizer (CK) as control. The results showed that the soil microbial biomass was higher in soil treated with CFM than in soil treated with CF alone, and that NPKM gave the highest rice and wheat yields. The SMBC and SMBN were higher after rice than those after wheat cropping. SMBC correlated closely with soil organic matter. Average yields of wheat and rice for 22 years were higher and more stable in the fertilized plots than in control plots. Bacterial community structure was analyzed by PCR-DGGE targeting eubacterial 16S rRNA genes. A higher diversity of the soil bacterial community was found in soil amended with CFM than in other fertilizer treatments. Some specific band emerged in the soil amended with M. The highest diversity of bacterial communities was found in the NPKM treated soil. The bacterial community structures differed in rice and wheat plots. Sequencing of PCR products separated in DGGE showed that some of the common and dominant bands were closely related to Aquicella lusitana and to Acidobacteria. This study demonstrated that mixed application of N, P, and K with additional M amendment increased soil microbial biomass, diversified the bacterial communities and maintained the crop production in the Calcareous Purplish Paddy soil.     

Effect of 46 years' application of fertilizers,FYM and lime on physical,chemical and biological properties of soil under maize–wheat system in an acid Alfisol of northwest Himalayas

Imbalanced fertilizer use with intensive cropping has threatened the sustainability of agroecosystems, especially on acid soils. An understanding of the long-term effects of fertilizers and amendments on soil health is essential for sustaining high crop yields. The effects of application of fertilizers, and amendments for 46 years on soil properties and maize yield in an acid Alfisol were investigated in this study. Ten fertilizer treatments comprising different amounts of NPK fertilizers, farmyard manure (FYM) and lime, and one control, were replicated three times in a randomized block design. At 0–15 cm soil depth, bulk density was least (1.20 t/m³), porosity (49.8%) and water holding capacity (61.7%) were greatest in 100% NPK + FYM, corresponding to the largest organic carbon content (13.93 g/kg). Microbial biomass C and dehydrogenase activity in 100% NPK + FYM were 42% and 13.7% greater than 100% NPK, respectively. Available nutrients were significantly more with 100% NPK + FYM and 100% NPK + lime than control and other fertilizer treatments. At 15–30 cm depth, the effect of various treatments was comparable to the surface layer. Grain yield declined by 55% and 53% in 100% NPK(-S) and 100% NP, respectively, compared with 100% NPK, whereas 100% N as urea alone eventually led to crop failure. Soil porosity recorded the greatest positive correlation (r = .933**), whereas bulk density recorded a negative significant correlation (r = −.942**) with grain yield. The results suggest that integrated use of FYM/lime with chemical fertilizers is a sustainable practice in terms of crop yield and soil health, whereas continuous application of urea alone is detrimental to the soil health.     

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.     

Long-term effects of fertilization and manuring on productivity and soil biological properties under rice (Oryza sativa)–wheat (Triticum aestivum) sequence in Mollisols

Long-term effects of chemical fertilizers and farmyard manure (FYM) in rice (Oryza sativa)–wheat (Triticum aestivum) cropping system were monitored for two consecutive years after 38 and 39 years on productivity and soil biological properties of Mollisols. The study encompasses varying chemical fertilizer levels of optimum fertilizer rate (120, 26 and 37 kg ha^?1 N, P and K, respectively) for both the crops. The treatments were application of 50% NPK, 100% NPK, 150% NPK, 100% NPK + hand weeding (HW), 100% NPK + Zn, 100% NP, 100% N, 100% NPK + 15 t FYM ha^?1, 100% NPK(-S) and unfertilized control. The rice and wheat yields were highest with 100% NPK + 15 t FYM ha^?1. This treatment also gave maximum and significantly more counts of bacteria, fungi and actinomycetes in soil than all the other treatments after crop harvest. The soil microbial biomass C (410.0 and 407.5 µg g^?1) and N (44.53 and 48.30 µg g^?1) after rice and wheat, respectively, were highest with 100% NPK + 15 t FYM ha^?1, which were significantly higher over all the other treatments. The activities of soil enzymes like dehydrogenase, acid and alkaline phosphatase, arylsulphatase and urease and CO₂ evolution rate with 100% NPK + 15 t FYM ha^?1 were also found significantly higher over the other treatments. Fertilizer treatments with 100% NPK and 150% NPK were comparable and significantly better than application of 50% NPK, 100% N, 100% NP and 100% NPK(-S) in various studied soil biological properties. Integrated use of 100% NPK with FYM sustained the higher yields and soil biological properties under rice–wheat cropping system in Mollisols. Application of Zn and hand weeding with 100% NPK were found better over 100% NPK alone in rice and wheat productivity. Imbalanced use of chemical fertilizers had the harmful effect on soil biological health.