陇东黄土高原旱作区冬小麦平衡施肥模式研究

以冬小麦"陇育4号"为供试作物,采用四元二次正交旋转组合设计开展商品有机肥与氮肥、磷肥、钾肥配施旱地冬小麦肥效试验,根据试验数据拟合出旱作冬小麦肥料效应方程及最佳肥料配比组合。结果表明:肥料合理配施可以增加旱地冬小麦有效分蘖数及次生根、促进冬小麦生长发育,从而增加冬小麦单位面积穗数、穗粒数、千粒重,提高籽粒产量;冬小麦最高产量为5452.54 kg hm~(-2),较对照增产20.6%,该最高产量对应的施肥量为N 155.25 kg hm~(-2)、P_2O_552.50 kg hm~(-2)、K_2O 17.55 kg hm~(-2)、OM168.75 kg hm~(-2);旱作冬小麦N(X_1)、P_2O_5(X_2)、K_2O(X_3)、OM(X_4)肥料效应函数为Y=4521.42+41.79X_1-41.29X_2-43.96X_3+7.62X_4-14.31X_1X_2+15.06X_1X_3-183.81X_1X_4-69.06X_2X_3+301.56X_2X_4+72.19X_3X_4+98.61X_1~2+51.11X_2~2+47.74X_3~2+126.49X_4~2,最佳肥料配比组合为N∶P_2O_5∶K_2O∶OM=1∶0.34∶0.11∶1.09。     

辽宁花生施肥模型试验研究

采用二次回归"3414"试验设计,对辽宁花生种植区的施肥数学模型进行了研究,配置出三元肥料效应函数模型Y=2693.10+360.87N+141.53P+104.95K-9.90NP+12.59NK+31.03PK-62.52N2-31.18P2-30.88K2和一元肥料效应函数模型Y=3065.64+576.51N94.86N2;Y=3395.34+346.48P51.02P2;Y=3099.21+366.55K43.82K2并分别推荐了最高产量为3960kghm-2及施肥量N为51kghm-2;P2O5为56kghm-2,K2O为70kghm-2为肥料研究工作者提供了丰富的施肥信息。     

有机肥/秸秆替代化肥模式对设施菜田土壤氮循环功能基因丰度的影响

  【目的】  利用天津市农业科学院西青区基地日光温室的蔬菜有机肥/秸秆替代化肥模式定位试验,分析不同施肥模式下设施春茬番茄盛果期土壤氮循环功能基因丰度、硝化潜势(PNR)及N₂O排放量的差异,为设施菜田可持续健康发展提供科学依据。  【方法】  定位试验始于2009年,共设置来源于化肥(CF)、有机肥(M)和玉米秸秆(S)不同比例的6个等氮磷钾处理,分别为:4/4CF、3/4CF+1/4M、2/4CF+2/4M、1/4CF+3/4M、2/4CF+1/4M+1/4S、2/4CF+2/4S。在第20茬设施蔬菜(春茬番茄盛果期)采集0—20 cm土壤样品,测定土壤氮循环相关指标。  【结果】  1)含有机肥/秸秆处理土壤的PNR较4/4CF处理平均增加72.9%,其中仅配施有机肥3个处理平均增加了107.0%,而配施秸秆两个处理显著低于含有机肥的2/4CF+2/4M、1/4CF+3/4M处理。 2)与4/4CF处理相比,有机肥/秸秆替代处理土壤反硝化过程功能基因NapAB、NirS、NorB、NosZ丰度平均分别增加了19.9%、20.4%、19.1%、2.3%,硝酸盐异化还原成铵过程功能基因NirB丰度平均增加了25.9%,而土壤硝化过程功能基因AmoA、AmoB、AmoC、Hao,以及硝酸盐异化还原成铵过程功能基因NrfH丰度平均分别降低了37.9%、46.3%、33.8%、65.5%、8.8%。3)与4/4CF处理相比,有机肥/秸秆替代处理土壤0～28 天 N₂O累计排放量平均增加了59.6%。4) Spearman相关性分析表明,土壤PNR与土壤有机碳(r = 0.37)、铵态氮(r = 0.47)、土壤N₂O累计排放量(r = 0.56)以及反硝化过程功能基因NapAB (r = 0.78)、NirK (r = 0.21)和NorB (r = 0.53)呈显著正相关关系,与土壤pH (r = –0.40)呈显著负相关关系;土壤N₂O累计排放量与土壤有机碳(r = 0.90)、全氮(r = 0.83)、硝态氮(r = 0.83)、铵态氮(r =0.64)及反硝化过程功能基因NapAB (r = 0.67)、NirK (r = 0.49)、NirS (r = 0.36)和NorB (r = 0.88)呈显著正相关关系,与土壤pH (r = –0.52)和硝化过程功能基因AmoA (r = –0.62)、AmoB (r = –0.64)、AmoC (r = –0.71)和Hao (r = –0.77)呈显著负相关关系。冗余分析显示,土壤硝态氮(P = 0.01)、铵态氮(P = 0.03)和有机碳(P = 0.05)对土壤氮循环功能微生物影响显著,分别解释其群落结构变异的34.0%,13.3%和11.3%。  【结论】  同等氮磷钾养分投入量下,有机肥/秸秆替代部分化肥,尤其是配施1/4有机肥及1/4秸秆模式(2/4CF+1/4M+1/4S)可显著降低土壤硝化过程功能基因丰度,增加反硝化、硝酸盐异化功能基因丰度,促进番茄盛果期的氮素吸收,减少可能向下淋洗的氮量。     

新乡市粮棉油料作物优化施肥决策的研究

对新乡市小麦、玉米、水稻、棉花、花生五大农作物优化施肥决策的研究,分别建立以产量为目标函数的氮磷效应模型y=b0+b1N+b2P+b11N2+b22P2+b12NP,根据模型计算得出,各作物不同产量水平的最大及经济最佳施肥量,经实践反馈验证,增产效应显著。     

临夏州马铃薯晚疫病始发期的预测预报

马铃薯是临夏州主要种植作物,随着种植区域的扩展,马铃薯晚疫病危害程度呈上升趋势,已成为制约马铃薯产业发展的主要因素之一。传统的晚疫病预测预报技术参数主要来源于干旱山区,在川塬区和二阴区预报准确率较低。本文依据多个试验点连续3a的观测资料,研究得出2个较好的预测模型：临夏州干旱山区马铃薯晚疫病始发期（Y）与8月上旬降水量（X）之间呈显著负相关关系,其线性回归方程为Y=9.1699-0.0153X（F=35.8〉F0.01）,预测准确率达到100%;二阴区马铃薯晚疫病始发期与7月上旬温度（X1）、空气湿度（X2）呈显著负相关,其线性回归方程为Y=13.8180-0.1970X1-0.0403X2,预测准确率达到83%。     

吉林省玉米施钾增产效应及区域差异

【目的】本研究利用测土配方施肥项目田间试验的大样本数据,分析吉林省玉米施钾增产效应在生态区及县域尺度上的差异,为促进玉米高产稳产和钾肥资源高效利用提供参考。【方法】基于2005-2013年吉林省玉米"3414"田间试验中推荐施钾(N2P2K2)和不施钾(N2P2K0)处理,分析生态区及县域尺度上玉米施钾的产量反应、农学利用率和肥料贡献率,建立玉米施钾产量、钾肥贡献率与基础产量之间的关系,从而评估吉林省玉米施钾的增产效应及区域差异。【结果】不施钾条件下,吉林东部湿润山区、中部半湿润平原区和西部半干旱平原区玉米的基础产量平均分别为8.44 t/hm^2 (3.29~14.5 t/hm^2)、9.45 t/hm^2 (3.77~15.3 t/hm^2)和8.11 t/hm^2(3.89~12.84 t/hm^2)。施用钾肥显著提高三大区域玉米产量,东、中、西部平均分别增产1.31 t/hm^2 (18.1%)、1.06t/hm^2 (12.2%)和1.30 t/hm^2 (17.4%)。推荐施钾条件下,东、中、西部玉米施钾的平均农学利用率分别为19.7、14.6和20.2 kg/kg,平均肥料贡献率分别为13.9%、10.2%和13.6%。统计分析显示,三大区域之间玉米施钾的增产量无显著差异,东部增幅显著高于中部,农学利用率和肥料贡献率东部也显著高于中、西部。回归分析发现,各区域玉米的施钾产量均与基础产量呈极显著正相关关系,符合线性模型,东部为y=0.769 x+3261 (R^2=0.616^**),中部为y=0.883 x+2158 (R^2=0.757^**),西部为y=0.873 x+2328 (R^2=0.637^**);而钾肥贡献率均与基础产量呈极显著负相关关系,符合对数模型,东部为y=–28.4 ln(x)+270.1 (R^2=0.348^**),中部为y=–15.9 ln(x)+156.1 (R2=0.172^**),西部为y=–16.3 ln(x)+160.6 (R2=0.123^**)。随土壤基础供钾能力的提高,东部玉米施钾产量的增幅和钾肥贡献率的降幅明显高于中、西部。【结论】吉林省玉米的钾肥管理应根据区域土壤钾素状况、自然气候条件和钾肥效应进行合理配置,现阶段应适当增加东部湿润山区玉米生产的钾肥资源配置,提高土壤供钾能力,促进玉米高产稳产。     

功能性肥料对制种玉米田物理性质和微生物数量的影响及最佳施肥量的研究

在甘肃河西内陆灌区的灌漠土上,采用田间试验方法,研究了功能性肥料对制种玉米田物理性质、微生物数量的影响及最佳施肥量。结果表明：影响玉米产量的因素由大到小依次为：CO(NH2)2>(NH4)2HPO4>抗重茬剂和聚乙烯醇。因素间最佳组合是：A3B2C1D1(即抗重茬剂30 kg/hm2,CO(NH2)2 600 kg/hm2,(NH4)2HPO4 350 kg/hm2,聚乙烯醇30 kg/hm2)。功能性肥料施用量与制种玉米田总孔隙度、毛管孔隙度、非毛管孔隙度、团聚体、微生物数量呈线性正相关关系,与制种玉米田体积质量呈线性负相关关系。随着功能性肥料施用量梯度的增加,玉米边际产量、边际利润在递减,功能性肥料施用量在1 350 kg/hm2的基础上,再增加337.50 kg/hm2,收益出现负值。经回归统计分析,功能性肥料施用量与玉米产量间的肥料效应回归方程是：y = 3 782.61 + 1.650 5x - 0.000 378 7 x2,功能性肥料经济效益最佳施肥量(x0)为1 350.01 kg/hm2,玉米理论产量(y)为6 700.99 kg/hm2,计算结果与最佳施用量试验处理5相吻合。     

不同培肥对煤矿区复垦土壤酶活性及微生物量碳、氮的影响

采用玉米盆栽试验,研究了不同培肥处理对平朔大型露天煤矿复垦土壤的熟化效果。结果表明:有机肥+菌肥+化肥各处理(Y1J1H1+Y2J2H2+Y3J3H3)对土壤速效P和有机质的增加最明显;有机肥+菌肥配施较低浓度化肥(Y1J1H1+Y2J2H2)对土壤碱解氮、磷酸酶、微生物量氮的增加最明显;有机肥+菌肥配施低浓度化肥(Y1J1H1)对土壤脲酶和微生物量碳的增加最明显;有机肥+菌肥各处理(Y1J1、Y2J2和Y3J3)对土壤速效K的增加最明显;单施有机肥各处理(Y1、Y2和Y3)对土壤pH的增加最明显;各处理的土壤过氧化氢酶差异不显著。相关分析表明,土壤磷酸酶、脲酶和微生物量碳、氮与碱解氮的相关性较好,微生物量氮与速效磷、pH的相关性较好。     

红壤侵蚀坡地上百喜草的施肥效应和合理施肥技术

在红壤侵蚀坡地小区试验条件下，进行百喜草N、P、K肥效试验和单施N肥效应研究，结果表明：在供试土壤区域，促进百喜草生长及鲜草量的最优施肥方案为氮肥单施，施用氮肥的曲线回归模型为Y=b0＋b1x＋b2x^2-b3x^3，效应方程为Y=51000．0＋275．5995x＋3．3750x^2-0．1335x^3，合理的氮肥用量范围为189．0～598．5kg／hm^2，经济最佳氮肥施用量为250．5kg／hm^2。     

无机氮与蔬菜废弃物耦合对土壤氮矿化的影响

为探明有机废弃物添加量与不同无机氮水平耦合对土壤氮矿化的影响,设计了3个甘蓝废弃叶添加量[B1:200 g.kg 1(土),B2:400 g.kg 1(土),B3:550 g.kg 1(土)]和4个无机氮水平[N0:0 mg.kg 1(土),N1:25mg.kg 1(土),N2:50 mg.kg 1(土),N3:100 mg.kg 1(土)]交互的控制培养试验(25℃,65%的田间持水量)。试验结果显示:各氮处理下土壤净累积氮矿化量是空白对照的4～5倍,N1水平下土壤净累积氮矿化量显著高于其他氮水平。各甘蓝废弃叶添加量处理下土壤净累积氮矿化量是空白对照的3～5倍,且B2添加量下土壤净累积氮矿化量显著高于B1和B3。统计分析表明,氮处理和甘蓝废弃叶添加量之间的交互效应不显著(P=0.275),甘蓝废弃叶的添加是影响氮矿化的主要因素(Eta2=0.16),而供氮水平为次要因素(Eta2=0.07)。B1添加量下,培养前期(0～20 d)土壤净累积矿化量逐渐升高,后期保持稳定水平;但B2和B3添加量下,培养前期(30 d)土壤呈现矿化、固持、再矿化现象,后期土壤净累积矿化量逐渐升高。氮矿化速率结果说明,甘蓝废弃叶添加后氮素矿化主要发生在培养前30 d。对培养期间土壤净累积氮矿化量随时间变化做一级动力方程模拟,拟合效果良好(R2=0.62～0.89)。     

作物生长中光照和氮肥施用量的相互关系研究

应用盆栽试验,在人工气候箱内进行的研究结果表明:光照强度(X1,mol/m2·s)和氮肥施用量(X2,g/pot)均对莴笋生长及生物量产生影响,且二者的变化与莴笋生物量的关系可表示为y＝-0.375+0.0230X1+9.421X2+0.0251X1X2-0.131×10-4X21-17.794X22形式; 不同光照强度下氮肥施用量与莴笋生物量的关系均可表示为y＝b0+b1X+b2X2形式;不同氮肥施用量下,光照强度与莴笋生物量的关系亦可用二次或三次多项式来表示.根据研究结果,还求得了氮肥施用量(X2)与光照强度(X1)的关系为:X2＝0.446-0.477×10-2X1+0.269×10-4X21-0.394×10-7X31.此外,本研究还探讨了光照强度、氮肥施用量与莴笋的氮素营养状况的关系.     

Response of summer‐planted potatoes to level of applied nitrogen and water

The irrigation and nitrogen (N) requirements of potatoes (cv. Delaware) were determined using sprinklers in a line‐source design on a Spearwood sand. Irrigation water was applied at 73 to 244% of the daily pan evaporation (Epan) and N at 0 to 800 kg N ha^‐1 (total applied) as NH₄NO₃ in 10 applications post‐planting. There was a significant yield (total and marketable) response to irrigation, at all levels of applied N, and N at all levels of applied water (P<0.001). The interaction between irrigation and N was also significant (P<0.001). There was no significant yield response to irrigation from 149% Epan (i.e., W3 treatment) to 244% Epan (i.e., W6 treatment). Irrigation at 125 and 150% of Epan was required for 95 and 99% of maximum yield, respectively, as determined from fitted Mitscherlich relationships. Critical levels of N required for 95 (417 kg ha^‐1) and 99% (703 kg ha^‐1) of maximum yield were also determined from a Mitschlerlich relationship fitted to the average of the W3 to W6 treatments. The percent total N and nitrate‐N in petioles of youngest fully expanded leaves required for 95 and 99% of maximum yield was 1.78 and 2.11, respectively, at the 10 mm tuber stage, and 0.25 and 0.80% at the 10mm plus 14 day stage (from quadratic regressions). There was a significant (P≤0.001) increase in N uptake by tubers with level of applied N from 57 kg ha^‐1 at 0 kg applied N ha^‐1 to 190 kg ha^‐1 at 800 kg applied N ha^‐1 (from a Mitscherlich relationship fitted to the average of W3 to W6 treatments). After accounting for N uptake from soil reserves (57 kg N ha^‐1), apparent recovery efficiency (RE) of fertilizer N by tubers [RE=(Up‐Uo/Np) where Up=uptake of N by the crop, Uo=uptake in absence of applied N and Np is the level of applied N, expressed as a fraction] declined from 0.28 at 100 kg applied N ha^‐1 to 0.17 at 800 kg applied N ha^‐1. There was a linear increase in ‘after cooking darkening’ (i.e., greying) of tubers with increasing level of applied N. Conversely, ‘sloughing’ (i.e., disintegration) of tubers decreased (inverse polynomial) with increasing level of applied N. Rate of irrigation had no effect on these cooking qualities. Reducing applied irrigation and N from levels required for 99% of maximum yield to levels required for 95% of maximum yield would not lead to a significant reduction in profit. This would increase apparent recovery efficiency of applied N by plants, maintain tuber quality, and reduce the impact of potato production on the water systems of the Swan coastal plain.     

氮肥施用量对莴笋光合特性影响的研究

运用盆栽试验方法，研究了氮肥施用量对作物（莴笋）光合特性的影响。结果表明，不同的氮肥施用量不仅对莴笋产量具有较大的影响，而且在一定程度上影响莴笋的光合速率、光饱和点、光补偿点、叶绿素含量等光合特性。增施氮肥，使其光合速率、光补偿点、叶绿素含量均得到提高，但过量施用氮肥反而会导致光合特性向不利方向变化并引起莴笋产量的下降。     

不同氮磷钾用量下春玉米生物产量及其组分动态与养分吸收模式研究

采用田间小区试验方法研究了不同氮磷钾用量下春玉米生物产量及组分干重动态与养分吸收动态及模式。结果表明,不同氮磷钾用量下春玉米总生物量及粒重的增长均符合Logistic方程;营养体干重随时间的变化符合回归方程Y＝axe^bx;生物产量依子粒产量和营养体干重变化符合回归方程Y＝exp（a＋b₁x₁b₂x₂）。适宜的氮磷钾配比及施肥技术可促进玉米植株生有前期总生物量的积累以及生育后期干物质从营养体向千粒的转移,从而获得较高的产量。不同肥料用量下春玉米氮磷钾绝对量的积累均符合Logistic方程,肥料用量可明显影响到玉米养分吸收最大速率及其出现日期。用量适宜可获得较高的养分吸收最大速率,且其最大速率出现日期相对较早;每生产100kg玉米子粒,适宜氮（N）、磷（P）、钾（K）的吸收量分别为1．557～1．602,0．419～0．427和0．973～1．025kg。植株养分吸收适宜比例N：P：K为1：0．27：0．62～O．64。     

Modeling Effects of Soil Fertility of Nutrients and Precipitation of 22 Years on Sustainable Productivity and Profitability of Pearlmillet and Sorghum Rotation in Semi-arid Vertisols

Based on experiments conducted during 1988–2009 on rainfed pearl millet/sorghum with 9 treatments in Vertisols, an efficient treatment for sustainable productivity is identified. Twenty kg of nitrogen (N) from farmyard manure (FYM) + 20 kg N (urea) + 10 kg phosphorus (P) ha^?1 in pearl millet and 40 kg N (urea) + 20 kg P + 25 kg zinc sulfate (ZnSO₄) ha^?1 in sorghum gave maximum yield and rainwater-use efficiency, whereas 20 kg N (FYM) + 20 kg (urea) + 10 kg P ha^?1 in pearl millet and 40 kg (urea) + 20 kg P ha^?1 in sorghum and gave maximum soil N, P, and potassium (K) over years. The regression model of 20 kg N (crop residue) + 20 kg N (urea) + 10 kg P ha^?1 gave maximum R² for predicting sorghum equivalent yield separately through precipitation and soil variables, whereas 20 kg N (FYM) + 20 kg N (urea) + 10 kg P ha^?1 gave maximum R² under combined model of both variables. Treatment of 20 kg N (FYM) + 20 kg N (urea) + 10 kg P ha^?1 was superior for attaining maximum sorghum equivalent yield of 1062 kg ha^?1, net returns of Rs. 4805 ha^?1, benefit/cost (BC) ratio of 1.50, and 127 kg ha^?1 of soil N, 10.3 kg ha^?1 of soil P, and 386 kg ha^?1 of soil K over years.     

Extractable nitrogen using hot potassium chloride as a mineralization potential index

Inorganic nitrogen (N) in soils is a primary component of soil‐plant N buffering. This study was conducted to determine if non‐exchangeable ammonium‐nitrogen (NH₄‐N) could serve as an index of potentially mineralizable organic N which is an important sink in N buffering. Four long‐term winter wheat (Triticum aestivum L.) experiments that had received annual fertilizer N at 0 to 272 kg N ha^‐1 were used. Soils from these experiments were extracted by four 10 mL portions of 2M potassium chloride (KC1) at room temperature followed by extraction with 20 mL of 2M hot KC1. Extraction at 100°C for four hours using 3 g soil and 20 mL 2M KC1 was found to be the most effective. Hot KC1‐extractable NH₄‐N minus room temperature KCl‐extractable NH₄‐N was considered non‐exchangeable NH₄‐N. Non‐exchangeable NH₄‐N was correlated with the long‐term N rates, and believed to be a reliable index of potentially mineralizable organic N. The relationship was linear for NH₄‐N where the lowest N rate had the lowest extractable N. The mean non‐exchangeable NH₄‐N concentration ranged from 8.42 to 16.34 mg kg^‐1; whereas, nitrate‐nitrogen (NO₃‐N) ranged from 0.07 to 1.87 mg kg¹. Total inorganic N extracted was similar to that mineralized in a 42‐day aerobic water saturated incubation. In addition, using a linear‐plateau model, extractable NH₄‐N was highly correlated with long‐term average yield (R²=0.92). For the soils evaluated, this method provided a rapid measure of potentially mineralizable N.     

增苗节氮对早稻抛秧群体生物学特性及产量的影响

本研究在大田裂区试验下比较了3个氮肥水平[N1:105 kg·hm·2(节氮)、N2:135 kg·hm·2(节氮)、N3:165 kg·hm·2(常氮)]和3个抛秧密度[M1:27万穴·hm·2(常苗)、M2:31.5万穴·hm·2(增苗)、M3:36万穴·hm·2(增苗)]对‘湘早籼45号’抛秧群体生物学特性和产量的影响。结果表明:增苗节氮处理(N2M3)为产量最高的组合。株高、生育期受氮肥影响较大,密度影响不显著,N1比N3和N2的生育期分别延长7.0 d和3.4 d;氮肥、密度的增加对分蘖表现为相反的趋势,总体表现为茎蘖数随施氮量增加而增加,随密度增加而减少。通过对氮肥、密度与产量间进行二次多项式回归分析可知,产量最大值点Y=8.60 t·hm·2,对应施氮量为X1=127.5 kg·hm·2,密度为X2=48.0万穴·hm·2,其比常氮(165 kg·hm·2)节省氮肥22.7%。表明早稻抛秧可以通过增苗来弥补节氮所带来的产量损失,早稻施氮量和抛秧密度搭配时应该以"增苗节氮"为原则。最佳施氮量在127.5~135 kg·hm·2,最佳抛秧密度在36~48万穴·hm·2。综上所述,双季抛秧的季节性矛盾能通过早稻"增苗节氮"来解决,有利于减少环境污染,延缓农业生态系统水体富营养化。     

A rapid procedure to calculate lime requirements based on single titration with base

The lime requirement (LR) in 39 surface acid soil samples (0–30 cm) from western Greece was calculated using a single-addition titration of successive 3-mL 0.022 M calcium hydroxide [Ca(OH)₂]. Soil pH measurements and titrations were performed in soil/water (1:2) and in a soil/0.01 M CaCl₂ (1:2) suspension while being stirred. The results were referred to as ‘pH data group I’ and ‘pH data group II’, respectively. In each ‘pH data group’, the samples were separated into ‘pH data subgroups’, according to the total volume (mL) of 0.022 M Ca(OH)₂ added to increase the initial pH (pH_a) to a target value of 6.5 (pH_t). The fitted linear regression equation pH_t = b × volume + pH_a was used for each ‘pH data group’ to determine the slope b. The b-weighted mean for each ‘pH data group’ was calculated. The LR was then calculated as follows: Mg CaCO₃ ha^?1 = 0.495 (pH_t – pH_a)/b, where b is the average weighted mean from the two ‘pH data groups’ and is equal to 0.227. The validity of the above equation was confirmed after incubation with Ca(OH)₂ for 72 h. This procedure is simple and gives a rapid and accurate estimation of LR with respect to the environment.     

Grain yield and nitrogen use efficiency of various modern rice cultivars grown at different nitrogen levels

Field trials were conducted to study the responses of grain yield and nitrogen (N) use efficiency at five input rates (N₀, N_82.5, N₁₆₅, N_247.5, and N₃₃₀ kg ha^?1) in a set of nine of the most representative rice cultivars. Grain yields of rice across the nine cultivars were increased significantly by N level. All the cultivars contained a significant linear plus plateau or quadratic relationship between N levels and grain yields.The minimum yields (means of 2 years) at N₀, N_82.5, N₁₆₅, N_247.5, and N₃₃₀ level all occurred in No. 2 cultivar. Compared with the grain yield of No. 2 at different N levels, those of the maximum cultivars increased by 37.1 (No. 8), 39.1 (No. 7), 48.4 (No.3), 43.3 (No. 4), and 43.9% (No. 3), respectively. In 2011, the highest average apparent nitrogen recovery efficiency (ANRE) in grain of the 4 N levels occurred in No. 3 cultivar (45.9%), followed by No. 4, No. 6, and No. 1, and the highest average agronomic efficiency (AE) in grain of the 4 N levels occurred in No. 9 cultivar [29.0 kg (kg N)^?1], followed by No. 3, No. 1, and No. 4. For the second-season planting, the highest average ANRE occurred in No. 4 cultivar (28.4%), followed by No. 3, No. 5, and No. 6, and the highest average AE occurred in No. 5 cultivar [18.1 kg (kg N)^?1], followed by No. 4, No. 3, and No. 7. Overall, No. 3 and No. 4 cultivars were the ideal ones that not only increased the grain yield but also improved the N use efficiency.     

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.