Controlled‐release urea decreased ammonia volatilization and increased nitrogen use efficiency of cotton

Excessive nitrogen (N) fertilizer input leads to higher N loss via ammonia (NH₃) volatilization. Controlled‐release urea (CRU) was expected to reduce emission losses of N. An incubation and a plant growth experiment with Gossypium hirsutum L. were conducted with urea and CRU (a fertilizer mixture of polymer‐coating sulfur‐coated urea and polymer‐coated urea with N ratios of 5 : 5) under six levels of N fertilization rates, which were 0% (0 mg N kg⁻¹ soil), 50% (110 mg N kg⁻¹ soil), 75% (165 mg N kg⁻¹ soil), 100% (220 mg N kg⁻¹ soil), 125% (275 mg N kg⁻¹ soil), and 150% (330 mg N kg⁻¹ soil) of the recommended N fertilizer rate. For each type of N fertilizer, the NH₃ volatilization, cotton yield, and N uptake increased with the rate of N application, while N use efficiency reached a threshold and decreased when N application rates of urea and CRU exceeded 238.7 and 209.3 mg N kg⁻¹ soil, respectively. Ammonia volatilization was reduced by 65–105% with CRU in comparison to urea treatments. The N release characteristic of CRU corresponded well to the N requirements of cotton growth. Soil inorganic N contents, leaf SPAD values, and net photosynthetic rates were increased by CRU application, particularly from the full bloom stage to the initial boll‐opening stage. As a result, CRU treatments achieved significantly higher lint yield by 7–30%, and the N use efficiency of CRU treatments was increased by 25–124% relative to that of urea treatments. These results suggest that the application of CRU could be widely used for cotton production with higher N use efficiency and lower NH₃ volatilization.     

Potassium distribution in root and non‐root zones of two cotton genotypes and its accumulation in their organs as affected by drought and potassium stress conditions

A rhizobox experiment was conducted to compare the differences of soil potassium (K) distribution and absorption between two cotton (Gossypium hirsutum L.) genotypes under drought and K‐deficit conditions. Treatments included two levels of water (drought and optimum soil moisture: 25% and 35% volumetric water content) and K fertilizer rates (0 and 0.48 g potash kg^?1 soil) applied to two cotton genotypes (namely HEG and LEG). Both the genotypes showed significant differences in total K accumulation without exogenous K addition. After absorption, soil content of the readily available potassium (RAK) decreased rapidly. This promoted the conversion of the mineral K into slowly available potassium (SAK). Drought significantly decreased the cotton growth and K use efficiency, and thereby reduced the effect of K fertilizer. Consequantly, the contents of RAK and SAK were greatly increased. However, K bioavailability was decreased under water stress conditions. Differences in root parameters and soil microorganisms between two cotton genotypes were significantly increased and had marked relations with available soil K contents. This study provides important information for understanding the mechanism of K use efficiency, especially under water and K stress.     

Bio‐inoculant improves nitrogen‐use efficiency and cotton yield in saline soils

Improved nutrient‐use efficiency is important to sustain agricultural production. The goal of our study was to investigate the effects of Azovit® (Azotobacter chroococcum) inoculation of seed with N fertilization on crop yield, nutrient uptake, and N‐use efficiency (NUE) of irrigated cotton (Gossypium hirsutum L. cv. C‐6524) in secondary saline soil under continental climatic conditions of Uzbekistan. A randomized complete block design in a 4 × 2 split‐plot experiment was established in the fall of 2013. The main plot was N fertilization (0, 140, 210, and 280 kg ha^?1) and the subplot was Azovit inoculation. Azovit inoculation consistently increased the seed and lint yields of cotton by 25 and 27.9%, respectively, at 210 kg N ha^?1 compared to the respective control. Azovit with 210 kg N ha^?1 significantly increased the cotton harvest index by 21%, when compared to the control. Likewise, nutrient uptake and NUE of cotton were higher when N (210 kg ha^?1) was applied with Azovit, as compared to other treatment combinations. An extrapolation of the relationship of relative yield vs. N fertilization showed that Azovit at 210 kg N ha^?1 was sufficient to obtain near‐maximum cotton production (90%) with highest NUE, as compared to the respective control. The results suggest that Azovit with 210 kg N ha^?1 produces cotton yield higher and/or comparable with the currently used rates of 280 kg N ha^?1 or higher, suggesting savings of 70 kg N ha^?1 for cotton production in saline soils under continental climatic conditions.     

包膜氯化钾一次基施对棉花生长周期钾素供应、 产量及品质的影响

【目的】钾是影响棉花生长发育和纤维品质的重要因素,本文旨在探究一次基施控释钾肥对棉花产量、 品质和钾肥利用率的影响,为棉花合理施用钾肥提供理论依据。【方法】以国欣棉3号为试验材料,在氮磷肥相同的条件下,连续2年盆栽试验。设6个处理: 1)不施钾肥(CK); 2)一次基施普通氯化钾(KCl); 3)40%基施+60%初花期追施氯化钾(KClD); 4)一次基施硫酸钾(KS); 5)40%基施+60%初花期追施硫酸钾(KSD); 6)一次基施控释氯化钾(CRK),每个处理重复四次。测定了苗期、 蕾期、 初花期、 盛花期、 始絮期和收获成熟期土壤速效钾含量和棉花株高、 茎粗,调查了籽棉产量,分析了品质指标和钾素吸收量。【结果】控释钾肥一次性基施(CRK)较普通钾肥显著提高了初花期、 盛花期、 始絮期及收获期的土壤速效钾含量。CRK较KCl处理增产23.6%,比KS处理增产15.6%,比KClD处理增产16.0%,与KSD处理差异不显著。CRK较KCl处理显著提高了衣分值,其余处理间单铃重及衣分差异不显著。CRK显著提高纤维长度、 伸长率和断裂比强度,但马克隆值和整齐度与其他处理差异不显著。速效钾肥追施较一次基施处理显著增加了生物量和吸钾量,但均低于控释钾肥处理。CRK处理的钾素利用率较KCl处理显著提高41.9%~50.9%,较KS处理提高27.3%~29.9%,较KClD处理提高21.1%~25.2%。【结论】本试验采用的控释钾肥钾素释放高峰期(80~110天)与棉花养分吸收高峰基本吻合,在棉花上一次基施对不同生育期的钾素供应优于普通钾肥一次性基施,也好于普通钾肥基施加追施,较速效钾肥显著提高了棉花的产量、 品质和钾肥利用率。     

不同钾肥对甘蓝产量、品质和营养元素形态的影响

选择重庆地区适宜栽培的甘蓝品种,采用田间小区试验,研究不同种类和用量钾肥对甘蓝产量、品质和营养元素形态的影响,为无公害甘蓝生产确定合理的施钾技术提供科学依据。结果表明,不同施钾处理甘蓝生物产量和商品产量均显著提高(增量为4.3%~20.2%),两种钾肥均以中量水平(K2)增产最显著,但相同用量下钾肥种类间增产效果无显著差异,从肥料成本看以氯化钾更优。各处理均提高甘蓝氨基酸含量,以低量硫酸钾最优,增幅达56.9%;除中量氯化钾提高甘蓝维生素C含量6.8%外,其余处理均降低维生素C含量;各处理对甘蓝硝酸盐含量以降低为主,以高量硫酸钾降幅最大达12.3%;钾肥对甘蓝还原糖含量表现为提高,且以低量氯化钾最优。各处理均在一定程度上提高甘蓝矿质元素含量(Zn除外)。甘蓝各营养元素形态中,均以非蛋白态为主。不同钾肥处理蛋白氮含量与氨基酸含量呈极显著负相关(相关系数r=-0.820),蛋白磷与氨基酸含量呈显著正相关,而非蛋白磷含量与维生素C含量呈显著正相关;与氮、磷素形态相比,不同钾素形态与甘蓝品质间关系更为密切,其中全钾、蛋白钾含量与维生素C含量均呈显著正相关。综合各指标效应看,甘蓝适宜钾肥种类为氯化钾,且以中量施钾水平最优。     

聚合物包膜肥料中钾素释放特征及其模拟

以水和水饱和石英砂为介质,研究了2种聚合物包膜肥料中钾素的释放特征。结果表明,钾素释放主要受温度影响,同时还受到颗粒大小和形态的影响;在水饱和石英砂中溶出与在水中溶出差别不大。采用水为介质,以一聚合物包膜肥料养分释放的理论模型为基础,对影响聚合物包膜肥料钾素释放的因素进行了研究,并进行了灵敏性检验。结果表明,温度越高、包膜的厚度和颗粒半径越小时钾素释放越快,且试验结果和模拟结果达到极显著的相关性;模拟结果比实际结果明显偏低,但表现出了较好灵敏性和相关性,是一个具有理论基础和应用潜力的聚合物包膜肥料养分释放模型。     

不同用量包膜氯化钾对马铃薯产量、品质及土壤钾供应的影响

利用马铃薯盆栽试验,通过设置不施钾肥、普通氯化钾、30%、50%、70%以及全量(等量于普通氯化钾)包膜氯化钾的处理,研究不同用量包膜氯化钾对马铃薯产量、品质及土壤钾素供应的影响。结果表明:包膜氯化钾25℃静水浸泡的钾素日均释放量约为1.2%,符合控释肥行业标准,在土埋下的钾素释放率呈S型,于70~90天释放率达到最大值,与马铃薯块茎形成及膨大时期相吻合,有利于产量形成;较普通氯化钾,包膜氯化钾的马铃薯增产幅度为13.92%~36.54%;包膜氯化钾全量处理的Vc含量、可溶性蛋白及淀粉含量显著高于普通氯化钾,而包膜氯化钾全量施用的马铃薯还原性糖含量显著低于其他处理,降低幅度为13.9%~36.2%;包膜氯化钾钾素缓慢释放,满足植株后期对钾的需求,在块茎形成期后,包膜氯化钾50%以上用量处理的植株吸钾量显著高于其他处理;包膜氯化钾50%以上用量的土壤速效钾含量在块茎形成期后显著高于通氯化钾,同时,土壤水溶性钾与非特殊吸附钾含量较普通氯化钾分别增加8.4%~25.1%和9.3%~36.1%,土壤钾素供应充足。综上,包膜氯化钾50%以上用量有利于提高马铃薯产量、商品薯率和品质,同时增加土壤钾素供应。     

钾素营养对大蒜生长、光合特性及品质的影响

采用溶液培养试验探讨了钾对大蒜苗期生长、生理生化指标及品质的影响。供试营养液K+浓度分别为0、3.0、6.0、9.0和12.0 mmol/L。结果表明,K+浓度在0～6.0 mmol/L范围内,大蒜苗期生长量、色素含量、净光合速率、可溶性蛋白质及大蒜素含量随K+浓度升高而增加;当达到9.0 mmol/L时,上述指标则呈下降趋势。营养液中K+浓度为6.0 mmol/L时,大蒜叶片及假茎生长量、光合色素含量、光合速率及蒸腾速率均最大,假茎及叶片大蒜素含量分别比0 mmol/L时高出63.57%和62.04%,叶片可溶性蛋白质含量明显高于其他处理;假茎及叶片可溶性糖含量在K+浓度为9.0 mmol/L时最高。在施钾各处理间游离氨基酸含量差异不显著,但均显著低于不施钾处理。总之,钾能明显促进大蒜苗期假茎和叶片生长,增加叶片色素含量,极大改善叶片光合特性,提高大蒜幼苗营养品质。营养液K+浓度以6.0 mmol/L时表现最好。     

Soil available potassium affected by rice straw incorporation and potassium fertilizer application under a rice–oilseed rape rotation system

Data from 147 field trials were collected to study the influence of straw incorporation on soil potassium (K) under an intensive rice–oilseed rape rotation system, while pot experiments were conducted to evaluate the effects of rice straw incorporation on soil K availability. A significant correlation was observed between the soil available K and the relative yield (RRY) and the relative K uptake (RKU) of oilseed rape, with R² values ranging from 0.07 to 0.08 and from 0.10 to 0.11, respectively, when data were fitted to a logarithmic equation model. In approximately 30% of trials, RRY reached 90%, while soil test available K values were below the critical limit, indicating that soil K values at the time of sampling (within 1 week of rice harvest) underestimated the actual soil K supply capacity. The pot experiment results showed that soil available K was affected by straw incorporation and soil type in the fallow period. The NH₄OAc‐K and NaBPh₄‐K concentrations of soils increased at first, and then, plateaued after 28 days. Straw incorporation significantly influenced the critical soil K concentration, which is important for making accurate K fertilizer recommendation. These results suggested that straw K should be seriously considered in making K fertilizer recommendations. Extending the sampling time from 1 to 3 weeks after the harvesting of rice to stabilize the effects of straw incorporation may help achieve a more accurate evaluation of soil available K.     

滴灌条件下减量施钾对香蕉产量及土壤钾素平衡的影响

[目的]香蕉生长快,需要及时充足的水肥供应,特别是钾素的供应.研究滴灌条件下减量施钾对香蕉产量品质、钾肥利用率、钾素平衡及经济效益等的影响,为制定适合香蕉生产的水肥一体化施肥方案提供依据.[方法]2016-2018年,在福建漳州进行了为期3年的田间定位试验.在施用等量氮磷肥的基础上,以不施钾肥(K0)和常规灌溉施钾14...     

根区施用钾肥对烤烟产量、钾含量及钾素吸收的影响

为了探讨根区施用钾肥对黄淮烟区石灰土烤烟产量和钾素吸收利用的影响,采用田间试验,研究根区枸溶性钾肥与硫酸钾配施对烟叶产量、钾含量以及钾素吸收利用的影响。试验共设9个处理,分别为CK、CP_1、CP_2、WP_1、WP_2、CW_(1-50%)、CW_(2-50%)、CW_(1-75%)与CW_(2-75%)(CK表示对照,CP表示只施用枸溶性钾肥,WP表示只施用硫酸钾,CW表示枸溶性钾肥与硫酸钾配施;数字1、2表示施用量分别为225、300 kg/hm~2,百分数表示硫酸钾的配施比例)。结果表明,烟叶钾含量随生育期推进呈下降趋势,不同施肥处理各时期烟叶钾含量均高于CK;不同施肥处理下土壤钾素在垂直和水平方向上迁移距离较小,根区钾肥施用可直接有效的增加根区土壤速效钾含量;施钾(K_2O)300 kg/hm~2与225 kg/hm~2相比,可显著提高烟叶钾含量和钾肥利用效率(P0.05);CW_(2-75%)处理下烟叶钾含量、土壤速效钾含量和钾肥利用率最高,而CW_(2-50%)处理下烟叶产量最高。综上所述,根区施用含75%硫酸钾的枸溶性钾肥300 kg/hm~2(CW_(2-75%)处理)可有效改善黄淮烟区石灰土钾素养分,提高该区烤烟产量、钾含量与钾肥利用效率,达到优质高产。     

Effect of long‐term fertilization and manuring on potassium release properties in a Typic Ustochrept

A long‐term fertilizer experiment, over 27 years, studied the effect of mineral fertilizers and organic manures on potassium (K) balances and K release properties in maize‐wheat‐cowpea (fodder) cropping system on a Typic Ustochrept. The treatments consisted of control, 100% nitrogen (100% N), 100% nitrogen and phosphorus (100% NP), 50% nitrogen, phosphorus, and potassium (50% NPK), 100% nitrogen, phosphorus, and potassium (100% NPK), 150% nitrogen, phosphorus, and potassium (150% NPK), and 100% NPK+farmyard manure (100% NPK+FYM). Nutrients N, P, and K in 100% NPK treatment were applied at N: 120 kg ha^—1, P: 26 kg ha^—1, and K: 33 kg ha^—1 each to maize and wheat crops and N: 20 kg ha^—1, P: 17 kg ha^—1, and K: 17 kg ha^—1 to cowpea (fodder). In all the fertilizer and manure treatments removal of K in the crop exceeded K additions and the total soil K balance was negative. The neutral 1 N ammonium acetate‐extractable K in the surface soil (0—15 cm) ranged from 0.19 to 0.39 cmol kg^—1 in various treatments after 27 crop cycles. The highest and lowest values were obtained in 100% NPK+FYM and 100% NP treatments, respectively. Non‐exchangeable K was also depleted more in the treatments without K fertilization (control, 100% N, and 100% NP). Parabolic diffusion equation could describe the reaction rates in CaCl₂ solutions. Release rate constants (b) of non‐exchangeable K for different depth of soil profile showed the variations among the treatments indicating that long‐term cropping with different rates of fertilizers and manures influenced the rate of K release from non‐exchangeable fraction of soil. The b values were lowest in 100% NP and highest in 100% NPK+FYM treatment in the surface soil. In the sub‐surface soil layers (15—30 and 30—45 cm) also the higher release rates were obtained in the treatments supplied with K than without K fertilization indicating that the sub‐soils were also stressed for K in these treatments.     

Effect of zinc‐biofortified seeds on grain yield of wheat,rice, and common bean grown in six countries

Seeds enriched with zinc (Zn) are ususally associated with better germination, more vigorous seedlings and higher yields. However, agronomic benefits of high‐Zn seeds were not studied under diverse agro‐climatic field conditions. This study investigated effects of low‐Zn and high‐Zn seeds (biofortified by foliar Zn fertilization of maternal plants under field conditions) of wheat (Tritcum aestivum L.), rice (Oryza sativa L.), and common bean (Phaseolus vulgaris L.) on seedling density, grain yield and grain Zn concentration in 31 field locations over two years in six countries. Experimental treatments were: (1) low‐Zn seeds and no soil Zn fertilization (control treatment), (2) low‐Zn seeds + soil Zn fertilization, and (3) Zn‐biofortified seeds and no soil Zn fertilization. The wheat experiments were established in China, India, Pakistan, and Zambia, the rice experiments in China, India and Thailand, and the common bean experiment in Brazil. When compared to the control treatment, soil Zn fertilization increased wheat grain yield in all six locations in India, two locations in Pakistan and one location in China. Zinc‐biofortified seeds also increased wheat grain yield in all four locations in Pakistan and four locations in India compared to the control treatment. Across all countries over 2 years, Zn‐biofortified wheat seeds increased plant population by 26.8% and grain yield by 5.37%. In rice, soil Zn fertilization increased paddy yield in all four locations in India and one location in Thailand. Across all countries, paddy yield increase was 8.2% by soil Zn fertilization and 5.3% by Zn‐biofortified seeds when compared to the control treatment. In common bean, soil Zn application as well as Zn‐biofortified seed increased grain yield in one location in Brazil. Effects of soil Zn fertilization and high‐Zn seed on grain Zn density were generally low. This study, at 31 field locations in six countries over two years, revealed that the seeds biofortfied with Zn enhanced crop productivity at many locations with different soil and environmental conditions. As high‐Zn grains are a by‐product of Zn biofortification, use of Zn‐enriched grains as seed in the next cropping season can contribute to enhance crop productivity in a cost‐effective manner.     

土壤干旱条件下锰肥对夏玉米光合特性的影响

在盆栽条件下进行了土壤干旱时夏玉米施用微量元素锰的试验。通过测定拔节期玉米叶片气孔导度(Cs)、细胞间隙CO2浓度(Ci)、蒸腾速率(Tr)、光合速率(Pn)和水分利用效率(WUR)等指标,探讨了干旱胁迫下外源锰对夏玉米光合特性的影响。结果表明,施用锰肥能降低光合作用的气孔限制和非气孔限制,显著提高夏玉米光合能力。锰肥对夏玉米光合作用的影响在土壤干旱时尤为显著。土壤干旱情况下,锰肥可使玉米叶片Cs增加58.11%,Pn和WUR分别增加42.07%和50.00%,从而减轻了土壤干旱对玉米光合作用的抑制。     

低土壤肥力下秸秆还田和施钾对作物产量及土壤钾素平衡的影响

为了研究我国华北平原低肥力土壤条件下秸秆还田和施钾肥对作物产量和钾素平衡的影响,于2008年10月～2011年10月在中国农业科学院高新技术园区国家测土施肥中心实验室试验基地（河北省廊坊市）,通过3年6季的定位试验,比较了施钾与秸秆还田的增产效应、钾素吸收利用和作物土壤系统的钾素平衡状况。结果表明:在氮、磷肥充足的情况下,施用钾肥（NPK）、秸秆还田（NP+St）和秸秆还田配施钾肥（NPK+St）,均有明显的增产效应,表现为NPK+StNPKNP+StNP;不同施钾措施在夏玉米上的增产效果优于冬小麦;同一作物秸秆还田结合施钾肥的增产效果最好,降低了年度间的产量变异系数,在获得高产的同时,年际间产量稳定,有利于稳产;施钾肥和秸秆还田可显著提高小麦和玉米的钾素吸收总量; NPK+St、NPK、NP+St处理的钾素表观平衡系数分别为1.26,0.42,0.92。秸秆还田和施钾肥有利于钾素的收支平衡,减轻作物对土壤钾素的消耗,缓解土壤钾素肥力下降的程度,可维持土壤钾素肥力的稳定。     

增施氮钾和光照强度对不同品种莴笋光合特性和产量的效应

通过盆栽试验研究了增施氮钾和光照强度对不同品种莴笋光合特性和产量的效应。结果表明,增施氮、钾肥3个品种莴笋的净光合速率（Pn）增加,且随光照的增加而增加;其中以“双尖”的Pn最低,“大白甲”和“挂丝红”的Pn较高。不同施肥处理对“双尖”光合特性影响较小;“挂丝红”光合特性在低光照下以＋K处理正效应较大,中、高光照下以＋N处理正效应较大,这与增施氮钾肥对“大白甲”光合特性的效应相反。3个莴笋品种产量随光照的增加而增加,产量以“挂丝红”＞“大白甲”＞“双尖”。3个光照强度下,＋N、＋K处理提高了不同品种莴笋产量。在高光照下,氮、钾增产效率以“双尖”最大,“大白甲”最小;中光照以“大白甲”最大;低光照以“挂丝红”最小。低光照下,莴笋施钾增产效率＞施氮;而中、高光照下,“大白甲”和“挂丝红”的施氮增产效率＞施钾,而“双尖”则相反。表明低光照下应控制氮肥施用量、适量增加钾肥用量;而在光照强度大的季节或条件下视莴笋（作物）品种特性适量增施氮肥和科学调控氮、钾肥的施用量比,可获得良好的增产效果。莴笋的产量与光合特性密切相关,以Pn、Chla、Ci与产量间相关性较好。     

盛铃期补施钾肥对不同群体棉花光合特性和产量品质的影响

在大田条件下,采用随机区组设计,研究了中期(7月28日)补施75.kg/hm2钾肥对去叶枝常规密度群体和留叶枝稀植大棵群体后期棉花叶片光合特性和产量品质的影响。结果表明,两种不同类型棉花群体中期补施钾肥,均能延缓叶片衰老,保持生育后期有较高的叶面积,并能显著提高棉花生育后期主茎叶片叶绿素含量、光合效率、PSⅡ潜在光化学活性FV/FO、实际光化学效率ФPSⅡ和气孔导度Cs;显著降低非光化学猝灭系数(NPQ),从而提高了后期群体和叶片对光能的利用;有效地增加了总铃数和铃重,使子棉产量提高8.9%～9.3%,纤维比强度增强。     

包膜复合肥对夏玉米产量、氮肥利用率与土壤速效氮的影响

以郑单958为材料,比较研究了复合肥(CF)与包膜复合肥(CCF)对华北平原夏玉米产量、氮肥利用率及土壤速效氮与土壤氮素表观盈亏的影响。结果表明,1)玉米产量随施氮量增大而增大,施N.180.kg/hm2时,CCF处理高于CF处理,施N.90.kg/hm2时表现相反;2)与CF处理比较,CCF处理施N.180.kg/hm2时,氮肥利用率高5.3个百分点,施N.90.kg/hm2时低2.4个百分点;3)土壤速效氮含量一般随施氮量增大而提高,各时期表土层CCF处理较CF处理高,中、下土层表现相反。大喇叭口期之前,CF处理中、下土层土壤速效氮含量高于上土层(020.cm或040cm),而CCF180处理060.cm土层高于60120.cm土层;4)不施氮,各生育阶段均出现土壤氮素表观亏缺,且吐丝后亏缺量占总亏缺量近80%;土壤氮素表观亏缺量随施氮量增大而降低,两种肥料表现一致;同等施氮量下CCF处理亏缺量较CF处理低。包膜复合肥氮素释放较平稳,对土壤速效氮向下运移的控制较好,有利于减少氮素潜在的淋洗损失。综合考虑产量、氮肥利用与氮素损失等因素,包膜复合肥用量N.180.kg/hm2是吴桥试区夏玉米季较为理想的选择。     

低土壤肥力下施钾和秸秆还田对作物产量及土壤钾素平衡的影响

为了研究我国华北平原低肥力土壤条件下秸秆还田和施钾肥对作物产量和钾素平衡的影响,于2008年10月～2011年10月在中国农业科学院高新技术园区国家测土施肥中心实验室试验基地(河北省廊坊市),通过3年6季的定位试验,比较了施钾与秸秆还田的增产效应、钾素吸收利用和作物-土壤系统的钾素平衡状况。结果表明:在氮、磷肥充足的情况下,施用钾肥(NPK)、秸秆还田(NP+St)和秸秆还田配施钾肥(NPK+St),均有明显的增产效应,表现为NPK+St>NPK>NP+St>NP;不同施钾措施在夏玉米上的增产效果优于冬小麦;同一作物秸秆还田结合施钾肥的增产效果最好,降低了年度间的产量变异系数,在获得高产的同时,年际间产量稳定,有利于稳产;施钾肥和秸秆还田可显著提高小麦和玉米的钾素吸收总量;NPK+St、NPK、NP+St处理的钾素表观平衡系数分别为1.26、0.42、0.92。秸秆还田和施钾肥有利于钾素的收支平衡,减轻作物对土壤钾素的消耗,缓解土壤钾素肥力下降的程度,可维持土壤钾素肥力的稳定。     

控释氮肥对棉花叶片光合特性及产量的影响

以鲁棉研28号为材料,设计100%树脂包膜尿素基施、50%普通尿素+50%树脂包膜尿素基施和棉花控释专用肥基施3种控释氮肥处理,研究了等氮条件下,不同控释氮肥处理对棉花光合特性及产量的影响。结果表明,与生产对照(CK2)相比,100%树脂包膜尿素处理和棉花控释专用肥处理提高了植株上部叶片叶龄45和60 d的叶绿素含量、PSⅡ的活性(Fv/Fo)、光化学最大效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)和光化学猝灭系数(qP),从而使叶片保持了较高的净光合速率;单株结铃数分别增加了0.77和0.84个,子棉产量分别增加6.2%和5.0%,皮棉产量分别提高6.4%和4.3%,分别达极显著和显著差异。而50%普通尿素和50%树脂包膜尿素处理与生产对照CK2差异较小。