为明确缓/控释肥(slow/controlledrelease fertilizer, CRF)在水稻上的应用效果，连续2年在南方双季稻区第四纪红壤发育的水稻土上进行双季稻大田试验，比较了不施氮肥(CK)、推荐分3次施肥(OF)、一次性基施缓/控释肥(100CRF)和一次性基施80%缓/控释肥(80CRF)条件下，双季稻的产量形成、氮素吸收和利用的差异。结果表明, 2年4季产量平均表现为80CRF>100CRF>OF>CK，其中80CRF、100CRF和OF分别比CK增产25.32%、23.93%和22.54%(P<0.05)，而各施氮处理间无显著差异；2年籽粒平均吸氮量中，早稻100CRF、80CRF处理均显著高于OF处理(P<0.05)，晚稻100CRF处理显著高于OF处理(P<0.05)，但80CRF处理与OF无显著差异，秸秆吸氮量与籽粒一致。100CRF、80CRF处理下氮肥吸收利用率均显著高于OF处理(P<0.05)；氮肥农学利用率、氮肥偏生产力以80CRF最高，显著高于100CRF和OF处理(P<0.05)；2012年晚季80CRF的氮肥生理利用率、土壤氮素依存率最高，显著高于100CRF处理(P<0.05)，2013年早晚稻均以OF处理最高，显著高于100CRF处理(P<0.05)；2年定位试验中的80CRF处理与OF处理氮素生理利用率无显著差异。因此，一次性施用缓/控释肥产量水平与推荐分次施肥水平相当，但施用缓/控释肥能显著提高水稻氮素吸收量和含量。全量施缓/控释肥虽能提高早晚稻氮肥吸收利用率，但氮素生理利用率降低；在推荐施肥的基础上减量20%施用缓/控释肥的早晚稻氮肥吸收利用率、农艺利用率、偏生产力均显著提高，氮肥生理利用率与推荐施肥无差异；即在稳产的基础上，提高了氮素的利用效果，是值得推荐的施肥方式。

【目的】探究不同组分的脲甲醛缓释肥在夏玉米上的肥料效应，为制备夏玉米一次性施用的专用肥料提供理论依据，从而简化施肥步骤，节省施肥成本，提高肥料效益，减少养分损失，保护生态环境。【方法】试验以夏玉米品种郑单958为供试材料，连续2年在大田条件下，设置3种组分脲甲醛缓释肥处理（UF1、UF2、UF3）、常规施肥处理（CF）和不施肥处理（CK），研究不同组分脲甲醛对夏玉米产量、氮肥利用率、地上部氮素积累量、土壤无机态氮含量的影响。【结果】不同组分的脲甲醛肥效不同，UF1、UF2、UF3脲甲醛缓释肥均能够提高夏玉米产量及氮肥利用率，尤其以UF2效果最佳，与常规施肥处理相比，UF2处理2年平均增产7.63%，氮肥利用率提高16.43个百分点；UF1效果次之，平均增产6.53%，氮肥利用率提高12.30个百分点；UF3平均增产4.98%，氮肥利用率提高0.82个百分点。不同组分脲甲醛缓释肥其氮素释放速率也不同，与常规施肥相比，脲甲醛缓释肥处理在玉米苗期0—20 cm土层无机氮含量均较高，其中以UF2处理最高，达80.09 mg·kg^-1；UF1次之，含量为66.47 mg·kg^-1，UF3处理最低，为51.18 mg·kg^-1。大喇叭口期常规施肥处理追施60%尿素，土壤的无机态氮含量有一定地提高，灌浆期含量为27.46 mg·kg^-1。20—40 cm土层中，UF1、UF2在大喇叭口期到灌浆期土壤无机态氮含量较稳定，灌浆期后含量下降，其中UF1处理收获期含量低至13.40 mg·kg^-1，比CF处理低1.05 mg·kg^-1。UF2处理收获期土壤无机态氮含量为14.13 mg·kg^-1，较CF处理降低0.32 mg·kg^-1。而UF3收获期土壤无机态氮含量略高于其他处理，较CF高出1.51 mg·kg^-1。因此，一次性施用的脲甲醛缓释肥处理均可满足玉米整个生育期的养分需求。【结论】在不同组分脲甲醛缓释肥中，UF2处理获得了相对较高的产量和氮肥利用率，可作为华北平原北部中低产土壤的玉米专用缓释肥。

<div style="line-height: 150%">This experiment explored the effects of single application of seven types of slow- and controlled-release fertilizers on rice yield and various population characteristics.&nbsp; Based on a study of the nitrogen (N) release characteristics of these fertilizers, pot experiments were conducted in 2018 and 2019 with split fertilization (CK, urea applied split equally at basal and panicle initiation stages, respectively) as control, which assessed the effects on SPAD value, yield and yield components, dynamic changes of rice tillers and dry matter accumulation.&nbsp; The results showed that the N release characteristics of different types of slow- and controlled-release fertilizers were significantly different.&nbsp; Polymer-coated urea (PCU) showed a controlled-release mode and provided sustained release throughout the whole growth stages.&nbsp; Sulfur-coated urea (SCU) exhibited a slow-release mode, providing insufficient release at the middle and late stages.&nbsp; Urease inhibitor urea (AHA) and urea-formaldehyde (UF) yielded a rapid-release mode, with an explosive N release at the early stage and no release at the middle and late stages.&nbsp; These results showed that PCU delayed the peak seedling stage.&nbsp; Compared with CK, dry matter accumulation and SPAD showed no significant differences, and due to the continuous release of N throughout the growth stages, rice yield, spikelets per panicle, seed setting rate, and 1 000-grain weight were all increased.&nbsp; Owing to the lack of N supply at the late stage and the low number of spikelets, SCU led to a reduction of rice yield, which is nevertheless not statistically significant.&nbsp; AHA and UF were susceptible to environmental factors and had varying effects on rice yield.&nbsp; The results of this experiment indicated that given a fixed amount of N applied in a pot, the stronger the N supply capacity and the longer the effective duration time of the fertilizer, the higher the dry matter accumulation at the late growth stage, and the higher the rice yield.</div>

Higher demands of food led to higher nitrogen application to promote cropping intensification and produce more which may have negative effects on the environment and lead to pollution. While sustainable wheat production is under threat due to low soil fertility and organic matter due to nutrient degradation at high temperatures in the region. The current research explores the effects of different types of coated urea fertilizers and their rates on wheat crop under arid climatic conditions of Pakistan. Enhancing nitrogen use efficiency by using eco-friendly coated urea products could benefit growers and reduce environmental negative effects. A trial treatment included N rates (130, 117, 104, and 94 kg ha-1) and coated urea sources (neem coated, sulfur coated, bioactive sulfur coated) applied with equal quantity following split application method at sowing, 20 and 60 days after sowing (DAS). The research was arranged in a split-plot design with randomized complete block design had three replicates. Data revealed that bioactive sulfur coated urea with the application of 130 kg N ha-1increased chlorophyll contents 55.0 (unit value), net leaf photosynthetic rate (12.51 μmol CO2m-2s-1), and leaf area index (5.67) significantly. Furthermore, research elucidates that bioactive sulfur urea with the same N increased partial factor productivity (43.85 Kg grain Kg-1N supplied), nitrogen harvest index (NHI) 64.70%, and partial nutrient balance (1.41 Kg grain N content Kg-1N supplied). The neem-coated and sulfur-coated fertilizers also showed better results than monotypic urea. The wheat growth and phenology significantly improved by using coated fertilizers. The crop reached maturity earlier with the application of bioactive sulfur-coated urea than others. Maximum total dry matter 14402 (kg ha-1) recorded with 130 kg N ha-1application. Higher 1000-grain weight (33.66 g), more number of grains per spike (53.67), grain yield (4457 kg ha-1), and harvest index (34.29%) were obtained with optimum N application 130 kg ha-1(recommended). There is a significant correlation observed for growth, yield, and physiological parameters with N in the soil while nitrogen-related indices are also positively correlated. The major problem of groundwater contamination with nitrate leaching is also reduced by using coated fertilizers. Minimum nitrate concentration (7.37 and 8.77 kg ha-1) was observed with the application of bioactive sulfur-coated and sulfur-coated urea with lower N (94 kg ha-1), respectively. The bioactive sulfur-coated urea with the application of 130 kg N ha-1showed maximum phosphorus 5.45 mg kg-1and potassium 100.67 mg kg-1in the soil. Maximum nitrogen uptake (88.20 kg ha-1) is showed by bioactive sulfur coated urea with 130 kg N ha-1application. The total available NPK concentrations in soil showed a significant correlation with physiological attributes; grain yield; harvest index; and nitrogen use efficiency components, i.e., partial factor productivity, partial nutrient balance, and nitrogen harvest index. This research reveals that coating urea with secondary nutrients, neem oil, and microbes are highly effective techniques for enhancing fertilizer use efficiency and wheat production in calcareous soils and reduced N losses under arid environments.