Cover‐crop seeding‐date influence on fall nitrogen recovery

Planting cover crops after corn‐silage harvest could have a critical role in the recovery of residual N and N from fall‐applied manure, which would otherwise be lost to the environment. Experiments were conducted at the University of Massachusetts Research Farm during the 2004–2006 growing seasons. Treatments consisted of oat and winter rye cover crops, and no cover crop, and four cover‐crop dates of planting. The earliest planting dates of oat and winter rye produced the maximum biomass yield and resulted in the highest nitrate accumulation in both cover‐crop species. The average nitrate accumulation for the 3 years in winter rye and oat at the earliest time of planting was 60 and 48 kg ha^–1, respectively. In 2004 where the residual N level was high, winter rye accumulated 119 kg nitrate ha^–1. While initially soil N levels were relatively high in early September they were almost zero at all sampling depths in all plots with and without cover crops later in the fall before the ground was frozen. However, in plots with cover crops, nitrate was accumulated in the cover‐crop tissue, whereas in plots with no cover crop the nitrate was lost to the environment mainly through leaching. The seeding date of cover crops influenced the contribution of N available to the subsequent crop. Corn plants with no added fertilizer, yielded 41% and 34% more silage when planted after oat and rye, respectively, compared with the no–cover crop treatment. Corn‐silage yield decreased linearly when planting of cover crops was delayed from early September to early or mid‐October. Corn‐ear yield was influenced more than silage by the species of cover crop and planting date. Similar to corn silage, ear yield was higher when corn was planted after oat. This could be attributed in part to the winter‐kill of oat, giving it more time to decompose in the soil and subsequent greater release of N, while the rapidly increasing C : N ratio of rye can lessen availability to corn plants. Early plantings of cover crops increased corn‐ear yield up to 59% compared with corn‐ear yield planted after no cover crop.     

土壤高残留氮条件下施氮对夏玉米氮素平衡、利用及产量的影响

土壤残留氮是不容忽视的土壤氮素资源.通过田间小区试验研究了土壤高残留氮下不同施氮量(0、80、160、240和320 kg/hm2)对夏玉米土壤硝态氮积累、氮素平衡、氮素利用及产量的影响,分析了夏玉米的经济效益.结果表明,土壤剖面硝态氮积累量随施氮量的增加而增加,且施氮处理硝态氮积累量显著高于不施氮处理;各施氮处理土壤硝态氮在0-60 cm土层含量最高,在0--180 cm剖面呈先减少后增加的变化趋势.不施氮处理夏玉米收获后土壤无机氮残留量高达378 kg/hm2,随施氮量的增加,无机氮残留和氮表观损失显著增加.作物吸氮量、氮表观损失量与总氮输入量呈显著正相关,总氮输入量每增加l kg作物吸氮量增加0.156 kg,而表观损失量增加0.369 kg,是作物吸氮量的2.4倍.高残留氮土壤应严格控制氮肥用量,以免造成氮素资源的大量浪费.夏玉米籽粒吸氮量随施氮量的增加呈增加的趋势,氮收获指数呈降低的趋势.氮肥农学效率、氮肥生理利用率、氮肥利用率和氮素利用率在施氮量80 kg/hm2时最高,随施氮量的增加降低;增施氮肥能降低高残留氮土壤中氮肥的增产效果和利用率.综合考虑产量、氮素利用和环境效应,N 80 kg/hm2是氮素高残留土壤上玉米的合理施氮量.     

Biochar and inorganic nitrogen fertilizer effects on maize (Zea mays L.) nitrogen use and yield in moist semi-deciduous forest zone of Ghana

Abstract

Maize (Zea mays L.) is a major nitrogen consuming crop, as nitrogen is considered as an important determinant of its grain yield. Though inorganic fertilizer is widely recommended, the problem of high cost and inaccessibility limit its usage by resource poor farmers. Biochar application provides a new technology for both soil fertility and crop productivity improvement. With limited research on the suitability of biochar for soil improvement practices in Ghana, our objective was to determine the synergistic effect of biochar and inorganic fertilizer on the nitrogen uptake, nitrogen use efficiency, and yield of maize. Field experiment was conducted in Ghana, KNUST, in the major and minor raining seasons. Biochar was applied at 0, 5, 10, 15, and 20 t ha^?1 and fertilizer N applied at 0, 45, and 90?kg ha^?1. The results showed significantly (p??1 supplemented with 45?kg N ha^?1 increased N uptake by 200%, and grain yield by 213% and 160% relative to the control in the minor and major rainy seasons, respectively. The greater yield of maize recorded on biochar-amended soils was attributed to the improved N uptake and nitrogen use efficiency. In conclusion, our finding suggests that the application of combined biochar and inorganic N fertilizer is not only ecologically prudent, but economically viable and a practicable alternative to current farmers’ practice of cultivating maize in Ghana.     

改善根系生长捕获深层土中NO3-N最优化免耕玉米氮肥利用率

Subsoil acidity restricts root growth and reduces crop yields in many parts of the world. More than half of the fertilizer nitrogen(N) applied in crop production is currently lost to the environment. This study aimed to investigate the effect of gypsum application on the efficiency of N fertilizer in no-till corn(Zea mays L.) production in southern Brazil. A field experiment examined the effects of surface-applied gypsum(0, 5, 10, and 15 Mg ha~(-1)) and top-dressed ammonium nitrate(NH_4NO_3)(60, 120, and 180 kg N ha~(-1)) on corn root length, N uptake, and grain yield. A greenhouse experiment was conducted using undisturbed soil columns collected from the field experiment site to evaluate NO_3-N leaching, N uptake, and root length with surface-applied gypsum(0 and 10 Mg ha~(-1)) and top-dressed NH_4NO_3(0 and 180 kg N ha~(-1)). Amelioration of subsoil acidity due to gypsum application increased corn root growth,N uptake, grain yield, and N use efficiency. Applying gypsum to the soil surface increased corn grain yield by 19%–38% and partial factor productivity of N(PFPN) by 27%–38%, depending on the N application rate. Results of the undisturbed soil column greenhouse experiment showed that improvement of N use efficiency by gypsum application was due to the higher N uptake from NO_3-N in the subsoil as a result of increased corn root length. Our results suggest that ameliorating subsoil acidity with gypsum in a no-till corn system could increase N use efficiency, improve grain yield, and reduce environmental risks due to NO_3-N leaching.     

Effects of cover crops sown in autumn on N and P leaching

A field experiment with separately tile-drained plots was used to study the ability of oilseed radish (Rhaphanus sativus L.), as a cover crop sown after harvest of a main crop of cereals or peas, to reduce nitrogen (N) and phosphorus (P) leaching losses from a clay loam in southern Sweden over 6 years. In addition to oilseed radish in pure stand, two cover crop mixtures (hairy vetch (Vicia villosa) and rye (Secale cereale) for 3 years and oilseed radish in mixture with buckwheat (Fagopyrum esculentum) for 2 years) were tested. The cover crop plots (three replicates per treatment) were compared with unplanted plots as a control. Plots cropped with oilseed radish during autumn (August–November) had significantly smaller yearly mean N concentration in drainage water over 5 of 6 years compared with unplanted controls. Mineral N content in the soil profile in autumn was significantly less in oilseed radish plots than for control plots in all years. The cover crop mixtures of hairy vetch and rye or buckwheat and oilseed radish also showed the potential to reduce soil mineral N in autumn and N concentration in drainage water, compared with unplanted controls. The cover crops had no impact on P leaching. In conclusion, oilseed radish has the ability to reduce leaching losses of N, without increasing the risk of P leaching.     

补充灌溉及氮磷配施对黄土塬区冬小麦水分利用及产量的影响

采用裂区试验设计,对黄土塬区补充灌溉及氮磷配施条件下麦田土壤水分动态、作物产量及水分利用效率等进行研究。结果表明：1）冬小麦对土壤水分的利用深度随小麦生长发育逐渐加深,在越冬前期和孕穗期分别达1.2和2.2 m土层以下,不同处理土壤含水量在小麦生育前期差异不明显,孕穗后氮磷配施处理的土壤含水量显著低于不施肥处理;2）试验条件下,补充灌溉后同样施肥处理的作物产量与雨养相比,虽有增加但不显著;不论是雨养水平,还是补充灌溉水平,氮磷配施均表现出显著的增产效果,从低氮低磷到高氮高磷,增产幅度在134%到240%之间;3）氮磷配施能显著提高冬小麦水分利用效率,而补充灌溉后水分利用效率降低3%-30%,但未达显著水平;4）不同氮磷配施的增产效应高于补充灌溉,补充灌溉与高氮高磷处理有显著的水肥协同效应,能显著提高作物产量并保持较高的水分利用效率。     

小麦苗期施入氮肥在土壤不同氮库的分配和去向

应用盆栽试验和15N标记技术研究了小麦苗期施入N肥后土壤不同N库的动态。结果表明 ,施肥后 28d ,作物所吸收的土壤N占总吸N量的 58.1% ,吸收的肥料N占 41.9%。作物对肥料N的利用率达到 55.3% ,N肥在土壤中的残留率为 24.3% ,损失率为 20.4%。施肥后短期以NH4+-4 N存在的肥料N占施N量的 50.5% ,随着硝化作用的进行和作物的吸收 ,土壤中的NH4+-N显著下降。NO3--N在第 7d达到高峰 ,表现为先升高后降低的趋势 ,说明施肥后在 7d以前有强烈的硝化作用发生。施肥后 2d ,以固定态铵存在的肥料N占 33.7% ,至 28d ,仅占施入N量的 2.4% ,说明前期固定的铵在作物生长后期又重新释放出来供作物吸收。在施肥后第 7d ,肥料N以微生物N存在的量占施肥量的 15.2% ;至 28d来自肥料N的微生物N也几乎被耗竭 ,仅占施N量的 2.4%。随作物生长 ,肥料N在各个土壤N库中的数量均显著下降。在其它N库几乎被耗竭的情况下 ,至施肥后 28d主要以有机N的形式残留。在不种作物的条件下 ,土壤N素的矿化量很低 ,作物的吸收作用导致土壤有机N库不断矿化 ,施入N肥后 ,土壤N素的矿化量增加 ,表现为明显的正激发效应     

Soil macrofauna affect crop nitrogen and water use efficiencies in semi-arid West Africa

It is increasingly recognised that soil fauna have a significant role in soil processes affecting nutrient availability and crop performance. A field experiment was conducted in southern Burkina Faso (West Africa) to investigate the contribution of soil fauna to nutrient availability and crop performance after application of different organic materials with contrasting qualities. A split plot design with four replications was laid out. The main treatment was the use of insecticides, to establish plots without fauna next to plots with fauna. The sub-treatments consisted in the application of Andropogon straw, cattle dung, maize straw, compost or sheep dung and a control. Soil fauna significantly increased crop water use efficiency. Crop nutrient use efficiency was high with the use of easily decomposable organic material in the presence of soil fauna. Supplementing low quality organic resources with mineral nitrogen is required to optimise the effects of their interaction with soil fauna towards enhanced crop nutrient and water use efficiencies.     

The consequences of wheel-induced soil compaction and subsoiling for silage maize on a sandy loam soil in Belgium

In Belgium, growing silage maize in a monoculture often results in increased soil compaction. The aim of our research was to quantify the effects of this soil compaction on the dry matter (DM) yields and the nitrogen use of silage maize (Zea mays L.). On a sandy loam soil of the experimental site of Ghent University (Belgium), silage maize was grown on plots with traditional soil tillage (T), on artificially compacted plots (C) and on subsoiled plots (S). The artificial compaction, induced by multiple wheel-to-wheel passages with a tractor, increased the soil penetration resistance up to more than 1.5 MPa in the zone of 0–35 cm of soil depth. Subsoiling broke an existing plough pan (at 35–45 cm of soil depth). During the growing season, the release of soil mineral nitrogen by mineralisation was substantially lower on the C plots than on the T and S plots. Silage maize plants on the compacted soil were smaller and flowering was delayed. The induced soil compaction caused a DM yield loss of 2.37 Mg ha⁻¹ (−13.2%) and decreased N uptake by 46.2 kg ha⁻¹ (−23.2%) compared to the T plots. Maize plants on compacted soil had a lower, suboptimal nitrogen content. Compared with the traditional soil tillage that avoided heavy compaction, subsoiling offered no significant benefits for the silage maize crop. It was concluded that avoiding heavy soil compaction in silage maize is a major strategy for maintaining crop yields and for enhancing N use efficiency.     

Manure and nitrogen fertilizer effects on corn productivity and soil fertility under drip and furrow irrigation

A field experiment was conducted at the Arkansas Valley Research Center in 2005 through 2007 to study the effects of manure and nitrogen fertilizer on corn yield, nutrient uptake, N and P soil tests, and soil salinity under furrow and drip irrigation. Manure or inorganic N was applied in 2005 and 2006 only. There were no significant differences in corn yield between drip and furrow irrigation even though, on average, 42% less water was applied with drip irrigation. Inorganic N or manure application generally increased grain yield, kernel weight, grain and stover N uptake, and grain P uptake. Nitrogen rates above 67 kg ha^?1 did not increase grain yield significantly in 2005 or 2006, nor did manure rates in excess of 22 Mg ha^?1. High manure rates increased soil salinity early in the season, depressing corn yields in 2005 and 2006, particularly with drip irrigation. Salts tended to accumulate in the lower half of the root zone under drip irrigation. Residual nitrate nitrogen from manure and inorganic N application sustained corn yields above 12.0 Mg ha^?1 in 2007. More research is needed to develop best manure and drip irrigation management for corn production in the Arkansas Valley.     

春玉米产量、氮素利用及矿质氮平衡对施氮的响应

通过在辽宁省昌图县的田间试验,研究了不同施氮水平(0、60、120、180、240和300 kg hm-2)对春玉米产量、氮素利用及农田矿质氮平衡的影响。结果表明:春玉米产量随施氮量增加而显著提高,当施氮量高于N 240 kg hm-2时,产量有减少趋势;氮素当季利用率随施氮量增加先增加后降低,在施氮量180 kg hm-2时达到最大,为27.95%。随着施氮量增加,氮肥农学利用率、氮素吸收效率和氮素偏生产力均显著降低,而氮肥生理利用率和氮肥表观残留率均先增加后降低,这与氮肥表观损失率的变化正好相反。作物吸氮量随施氮量增加而显著增加,氮盈余主要以土壤残留为主,表观损失在氮盈余中的比例虽小,但随着施氮量增加而明显增加。低量施氮(<180 kg hm-2)主要引起土壤矿质氮残留量的显著增加,而高量施氮(240 kg hm-2和300 kg hm-2)主要引起土壤氮素表观损失量的显著增加。在本试验条件下,合理施氮量应控制在180～209 kg hm-2左右。     

萝卜适宜施氮量和氮肥基追比例研究

运用15N示踪法研究了大田条件下不同氮肥用量与施肥方式对萝卜氮素吸收、分配及肉质根产量的影响。试验设置3个氮水平（0、 60和120 kg/hm2）和两种基追肥比例［基肥∶破肚期肥料∶膨大期肥料=50%∶20%∶30%（A）和30%∶20%∶50%（B）］,共5个处理,依次记作 N0、N60A、N60B、N120A、N120B。结果表明,在施N 0120 kg/hm2范围内,随氮施用量的增加,萝卜吸收的肥料氮素、土壤氮素数量及肥料氮在土壤中的残留量显著增加,氮素的吸收利用率和土壤残留率显著下降,氮素损失率显著增加。当氮用量为120 kg/hm2 时, N120A和N120B处理萝卜吸收的肥料氮素、土壤氮素及肥料氮在土壤中的残留量分别为30.50、 53.64、 14.88 kg/hm2和35.56、 56.61、 17.81 kg/hm2,采收期肉质根产量分别为67.6 t/hm2和72.5 t/hm2,比对应的低氮处理（N60A和N60B）分别增加64.07%和66.67%,且N120B处理萝卜氮素吸收利用率显著提高。因此,适量施氮并增加肉质根膨大期的施氮比例,可有效提高氮肥利用率,显著增加萝卜肉质根产量。在本试验条件下,施氮量为120 kg/hm2, 按照基肥∶破肚期肥料∶膨大期肥料比例30%∶20%∶50%进行施肥,是兼顾产量和氮肥利用效率的最佳氮肥运筹方式。     

施氮与灌水对夏玉米土壤硝态氮积累、氮素平衡及其利用率的影响

通过田间裂区试验研究了不同施氮量(N 0、150、210和270 kg/hm2)和灌水量(900、1200、和1500 m3/hm2)对夏玉米土壤硝态氮分布累积、氮素平衡以及氮肥利用率的影响。结果表明,夏玉米收获期各处理土壤硝态氮在表层(0—20 cm)含量最高,在0—200 cm剖面均呈现先减少后增加再减少的变化趋势;土壤剖面NO3--N累积量随施氮量的增加而增加,且施氮处理硝态氮积累量显著高于不施氮处理。作物吸氮量、氮素表观损失量均与施氮量和总氮输入量呈显著相关,氮素输入量每增加1 kg,作物吸氮量仅增加0.301 kg,而表观损失量增加0.546 kg,是作物吸氮量的1.8倍左右。随施氮量的增加土壤剖面中NO3--N的损失量逐渐减少。夏玉米子粒吸氮量和收获指数随施氮量的增加有增加的趋势;氮肥回收效率和氮肥农学效率均以处理W1500N150最高,分别为46.15%和12.98kg/kg;氮肥生理效率以处理W1200N150最大,为34.49 kg/kg。本试验条件下,以水氮处理W1500N150的土壤硝态氮残留量、表观损失量较低,夏玉米氮肥回收效率和农学效率较高。     

SWAT模拟耕作方式与盐分对区域土壤氮运移及作物产量影响

耕作方式与土壤盐渍化是影响河套灌区氮素流失及作物产量的重要因素.明确不同耕作方式与盐渍化水平下硝态氮运移量及作物产量的变化,可为制定合理的灌区耕作措施及盐渍化治理方案提供理论依据,对于揭示灌区氮素流失控制及不同作物增产潜力具有重要意义.该研究基于验证后的SWAT(Soil and Water Assessment To...     

Effects of phosphorus-based application of animal manure compost on the yield of silage corn and on soil phosphorus accumulation in an upland Andosol in Japan

Animal manure contains significant amounts of nitrogen (N) and phosphorus (P) that can be utilized as fertilizer. However, manure application rates are generally set to meet crop N demand, which results in excess P application which increases the risk of P loss into bodies of water. We examined the application method of manure compost based on crop P demand on the dry matter yield of silage corn (Zea mays L. var. indentata), on nutrient uptake and on soil P accumulation in an upland Andosol with a high P-fixing capacity. Cattle and poultry manure composts (CMC and PMC) with different P solubility were applied to meet the crop’s N requirements (N-based application) or P requirements (P-based application) in 3 consecutive years. Supplemental N was applied using polyolefin-coated urea in the P-based treatments. The dry matter yields and nutrient uptakes of silage corn in the P-based CMC and PMC application systems were similar to those in the corresponding N-based systems. The average relative efficiency of N in CMC (33%) was close to the predicted value (30%) during the study. On the other hand, the relative efficiency of N in PMC (42%) was higher than the predicted value (28%). The average relative efficiency of P from CMC and PMC was 109% and 50%, respectively. These were higher than the predicted values based on the available P proportion (the sum of water- and sodium bicarbonate-soluble P) for CMC (78%) and PMC (34%), indicating that the available P fraction in the manure composts was more effective than that in P fertilizer for corn growth or that the other P fractions were also effective for corn. P-based manure compost application lowered the soil P accumulation to between 41 and 43% of the value in the N-based accumulation (versus a value of between 31 and 40% of that value for soil Truog-P). Compared to N-based manure compost application, P-based manure compost application with supplemental N fertilizer produced similar dry matter yields of corn and suppressed soil P accumulation in the upland Andosol field.     

应用Hydrus-1D模型模拟分析冬小麦农田水分氮素运移特征

将Hydrus 1D水氮联合模型用于模拟冬小麦农田水分氮素运移转化过程,试验和模拟结果表明,北京地区冬小麦农田不同水肥处理小区,蒸散量约400mm,占根层总耗水量的95%以上,水分渗漏到根层以下量很少,各小区最大渗漏量为38.4mm。作物吸氮占总耗氮量的94%以上,而根层以下氮淋失很少,最大氮淋失量为8.7kg/hm2。氮淋失量主要对应于水分渗漏量,可考虑改变灌溉措施减少水氮淋失量。传统水、肥管理方案与优化水、肥管理方案比较,各处理产量和水氮利用效率无显著差异,而前者根层水分渗漏量大并肥料总投入量大。综合评价认为,优化水肥管理措施更合理可取。     

Compost and Manure Effects on Fertilized Corn Silage Yield and Nitrogen Uptake under Irrigation

Abstract

Dairy manure increases the yields of dry bean (Phaseolus vulgaris L.) and spring wheat (Triticum aestivum L.) from eroded, furrow‐irrigated soils and may increase corn (Zea mays L.) silage yield from steeper eroded areas under sprinkler irrigation. In a 2‐year field study in southern Idaho on Portneuf silt loam (coarse silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid), the effects of a one‐time, fall application of 29 or 72 Mg ha^?1 of dry manure or 22 or 47 Mg ha^?1 of dry compost on subsequent silage yield and nitrogen (N) uptake from previously eroded, sprinkler‐irrigated hill slopes were evaluated. In October 1999, stockpiled or composted dairy manure was disked to a depth of 0.15 m into plots with slopes from 0.8 to 4.4%. After planting field corn in 2000 and 2001, a low‐pressure, six‐span traveling lateral sprinkler system was utilized to apply water at 28 mm h^?1 in amounts sufficient to satisfy evapotranspiration to 6.4‐×36.6‐m field plots. Yields in 2000 were 27.5 Mg ha^?1, similar among all rates of all amendments and a fertilized control. In 2001, compost applied at oven‐dry rates up to 47 Mg ha^?1 increased yield compared to controls. Silage yield in 2001 increased initially then decreased with increasing manure applications. Where compost or manure was applied, regardless of rate, 2‐year average N uptake was 15% greater than controls. Regardless of treatment or year, yields decreased linearly as soil slope increased.     

夏玉米污水灌溉时水分与氮素利用效率的研究

用田间实验研究污水灌溉条件下夏玉米水分与氮素的利用效率。试验设置了高、中、低3个不同灌水水平下的9个对比处理，结果表明：灌水量、灌溉水质、施肥量对夏玉米叶面积指数、株高和产量的影响很小；不同灌溉水量条件下，污水灌溉夏玉米的耗水规律与清水灌溉的耗水规律十分接近，且累积耗水量随灌溉水量的增大而增加；水分利用效率与灌溉水质和施肥无关，仅随灌溉水量的增加而减少。清水灌溉处理玉米的吸氮量高于污水灌溉处理玉米的吸氮量；氮的利用效率与灌水量和施肥无关，仅与灌溉水质有关，且污水灌溉氮的利用效率高于清水灌溉氮的利用效率。     

氮肥和接种根瘤菌对豌豆/玉米间作产量和水分利用效率的影响

豌豆/玉米间作是河西绿洲灌区面积最大的间作模式,也是当地重要的高产高效种植模式之一。针对目前氮肥过量施用和豆科作物生物固氮被忽视的实际,2011年和2012年在甘肃省武威市凉州区进行了豌豆/玉米间作大田试验,研究不同施氮量下,豌豆接种根瘤菌对豌豆/玉米间作体系作物籽粒产量和水分利用效率的影响,旨在为河西绿洲灌区豌豆/玉米间作体系节肥、高产的氮肥用量和接菌增产作用提供理论依据。结果表明:施用氮肥对豌豆产量影响不显著。接种根瘤菌后单作豌豆比不接菌处理两年平均增产12.7%,间作豌豆产量比单作两年平均增产61.1%,间作豌豆接种根瘤菌比不接菌两年平均增产4.8%。单作豌豆以施氮量75 kg(N)·hm-2接菌处理的产量最高,达到2 735 kg·hm-2;而且在此施氮量下接菌比不接菌两年平均增产达22.8%。施用氮肥对玉米的增产效果显著,施氮量在300 kg(N)·hm-2时单作玉米产量为14 394 kg·hm-2,间作比单作两年平均增产61.8%;间作豌豆带接菌较不接菌玉米两年平均增产3.3%。土地当量比在不同施氮量和接种根瘤菌的条件下都大于1。豌豆水分利用效率随施氮量增加而减小,最大值为不施氮的12.9 kg·mm-1·hm-2;玉米水分利用效率随施氮量增加先增大后减小,以施氮量300 kg(N)·hm-2处理为最高,达25.0 kg·mm-1·hm-2。综上所述,在豌豆/玉米间作体系中,玉米高产、高水分利用效率的施氮量为300 kg(N)·hm-2,豌豆高产高效的施氮量为75 kg(N)·hm-2。在大田生产中,接种根瘤菌对豌豆和玉米增产作用明显。     

Tillage and nitrogen effects on growth,nitrogen content,and yield of corn

Abstract

The use of conservation tillage methods, including ridge tillage, has increased dramatically in recent years. At the present time, there is great concern that farmers are applying more nitrogen (N) fertilizer than is environmentally or economically sound. In order to determine if N requirement for optimum yield differs with tillage system, tests were initiated to study tillage and N effects on N content, soil moisture content, and yield of corn (Zea mays L.). The study was established in 1987 on two soil types, an Estelline soil (Pachic Haploboroll) and an Egan soil (Udic Haplustoll), located in eastern South Dakota. Five rates of N (0, 65, 130, 195, and 260 kg ha^?1) were applied to plots managed with 3 tillage systems: chisel plow, moldboard plow, and ridge. On the Estelline soil, in both 1988 and 1989, ridge‐tilled plots contained a greater amount of water in the soil profile at emergence and at mid silk than did plots in the other two tillage systems. Soil moisture content at mid silk was significantly correlated with earleaf N, total N uptake, and grain yield in 1988 and earleaf N and grain yield in 1989. However, the correlation coefficients were higher in 1988 than in 1989. On the Egan soil, there were no significant differences in soil moisture content among tillage systems. On the Estelline soil, corn grain yield was affected by a tillage x N‐rate interaction in 1988. Maximum yield within the ridge system was achieved with the 130 kg ha^?1 rate. In 1989 on the Estelline soil, yield was affected by tillage and N rate, but there was no interaction between factors. When averaged over N rates, yields were 7.1, 6.6, and 6.5 Mg ha^?1 in the ridge, moldboard, and chisel systems, respectively. In 1988 plant total N uptake was greater in the ridge system than the moldboard or chisel systems; in 1989 uptake was affected by N rate alone. On the Egan soil, tillage did not affect soil moisture, total N uptake or grain yield in either year. Corn grain yield increased with increasing N rate up to the 195 kg ha^?1 rate. This study indicates that, on some soil types, ridge tillage can improve soil water holding capacity, N utilization and yield of corn.