叶面施氮对大豆“合丰50”叶片叶绿素含量及干物质积累的影响

以黑龙江省三江平原大豆主栽品种"合丰50"为试验材料,研究不同时期叶面施氮对大豆叶片叶绿素含量及干物质积累的影响。结果表明,在施肥量为N 5.0kg·hm~(-2)条件下,五叶期(V5期)叶面施氮后叶绿素含量SPAD值为56.4,无籽粒干物重为26.4g,始粒期(R5期)叶面施氮后籽粒干物重为25.0g,均高于其它处理。"合丰50"在R5期施肥量为N 5.0kg·hm~(-2)条件下产量最高。     

不同施氮水平对南方甜玉米氮素吸收利用的影响

【目的】探明南方鲜食玉米区高产条件下施氮量对甜玉米产量、氮素利用及其转运规律的影响。【方法】于2015年和2016年,选用国审甜玉米品种粤甜16为供试材料,设置N (0、100、150、200、250、300、450 kg/hm2) 7个施氮量处理进行连续2年的大田试验。在拔节期 (8片展开叶)、大喇叭口期 (12片展开叶)、雄穗开花期和乳熟收获期测定甜玉米植株及各器官干重、氮养分含量,研究分次施肥条件下,不同施氮量对甜玉米乳熟收获期植株体内的氮养分吸收积累与分配比例、氮收获指数和效率,以及对不同生育时期植株、叶片、茎鞘氮素积累的影响。【结果】在2个生长季,施氮量均显著影响甜玉米鲜穗产量、植株总氮素积累量、氮素收获指数、氮肥农学效率、氮肥利用率和氮肥偏生产力。随着施氮量 (0～450 kg/hm2) 的增加,鲜穗产量、植株氮素总积累量呈现先增加后保持上下小幅波动的趋势;氮肥农学效率先增加后下降;氮肥利用率、氮肥偏生产力持续下降。在施氮量为N 250 kg/hm2时,粤甜16的鲜穗产量、植株氮素总积累量达到或接近最高,两年平均值分别为17544 kg/hm2和145.6 kg/hm2;而氮肥农学效率达到最高值,两年平均值为48.4 kg/kg;氮素利用率和偏生产力两年平均值分别为28.5%、70.2 kg/kg,处于中间水平;鲜穗产量、植株氮素总积累量和氮肥农学效率均达到最大。施N 250 kg/hm2提高了茎鞘、叶片的氮素转运量和花后氮素同化量,氮素茎鞘转运、叶片转运和氮素花后同化对鲜穗的贡献率两年平均值分别为48.8%、10.2%、41.0%。甜玉米整株氮素积累随生育进程持续增加,乳熟期最高,日均最高积累速率在8展叶至12展叶期;叶片和茎鞘的氮素积累进程呈单峰曲线,在雄穗开花期达到峰值,日均最快积累速率分别在8展叶至12展叶、12展叶至雄穗开花期。施氮能提高各器官在各生育时期的氮素积累量和积累速率,但不改变氮素积累变化趋势。【结论】在本试验条件下,采用多次施肥,施N 250 kg/hm2可提高氮肥农学效率,有效调控开花前氮素转运及花后吸收同化,促进鲜穗氮素积累,实现甜玉米高产高效。     

春玉米产量和施氮量对氮素利用率的影响

提高氮素利用率是提高氮素收益、降低氮肥施用所带来的环境风险的重要途径。采用同一品种春玉米丰田6号,以无灌溉黑土为供试土壤,采用“3414”试验设计,经3年试验,对春玉米氮素利用效率与玉米产量和施氮量之间的关系进行了探讨。结果表明,氮肥利用率与产量呈显著的正相关,而与施氮量呈显著负相关。当玉米产量大于11 t/hm2,施氮水平控制在当地推荐施肥量时,氮肥利用率可高达45%以上;超过当地推荐施肥量,氮肥利用率随施氮量的增加急剧下降。当玉米产量低于6 t/hm2时,氮肥利用率徘徊在17%左右,并且随着施氮量的增加变化不明显。     

氮、磷和钾营养对优质玉米子粒产量和营养品质的影响

施用氮、磷和钾营养对优质玉米子粒产量和营养品质有明显的影响。氮磷钾营养平衡施用(NPK)较不施氮(PK)、不施磷(NK)和不施钾(NP)显著增加优质玉米产量,使高油玉米(农大115)分别增产15.9%、6.9%和12.1%,使高淀粉玉米(白玉109)依次增产20.3%、8.6%和12.7%。施氮能增加高油和高淀粉玉米子粒蛋白质、醇溶蛋白和清蛋白含量;施磷或施钾能增加高油玉米子粒蛋白质、醇溶蛋白和清蛋白含量以及氨基酸和必需氨基酸含量,而对高淀粉玉米子粒蛋白质及其组分含量基本无或较小影响。施氮使高油玉米子粒氨基酸和必需氨基酸含量提高0.83和0.41个百分点,使高淀粉玉米提高1.18和0.36个百分点;施氮、施磷和施钾增加高油和高淀粉玉米淀粉总量和支链淀粉含量,降低直链淀粉含量。施氮能增加高油和高淀粉玉米子粒油分、亚油酸和油酸含量,使高油玉米分别增加0.83、0.41和0.30个百分点,使高淀粉玉米分别增加0.34、0.18和0.13个百分点,而施磷或施钾对两品种子粒油分、亚油酸和油酸含量的影响不明显。     

氮施用水平和方式对高粱作物产量和质量的影响

A field study was conducted for two years at the Arid Zone Research Institute, Dera Ismail Khan, Pakistan, to determine the optimum level of nitrogen and efficient application method in the production of sorghum （Sorghum bicolor L.）. Using four levels of nitrogen, i.e., 0, 60, 90, and 120 kg ha^-1, and two different application methods （soil application and foliar spray）, the experiment was laid out in a split-plot design, where the main plots were used to determine the effective method of application and the subplots were used to detect the influence of N levels on the grain yield. The average data obtained after two years of study indicated an increase in the grain yields with an increase in N levels irrespective of the method used of N application. The grain yield increased from 2.92 to 5.61 t ha^-1 in the plots that were treated with 90 kg N ha^-1 compared with the control plots. Quadratic regression analysis showed that the increase in the yield was higher at the lower levels of N compared with the succeeding higher levels. The soil application method, producing an average grain yield of 4.79 t ha^-1, was found to be superior to the foliar spray method with an average grain yield of 4.56 t ha^-1. The protein content of the grain showed a linear increase with N application, attaining the maximum at 120 kg N ha^-1 in both the methods of N application. In addition, compared with the method of soil application, higher crude protein contents were observed using the method of foliar spray at all N levels.     

氮肥用量对高淀粉玉米和普通玉米吸氮特性及产量和品质的影响

采用田间试验研究氮肥用量对高淀粉玉米(郑单21)和普通玉米(四密25)吸氮特性及子粒品质产量的影响。结果显示,与普通玉米相比,高淀粉玉米氮素最大吸收速率较大,出现日期早,成熟期吸氮总量高,但其子粒产量却较低。高淀粉玉米子粒中的氮素更多依赖于后期的根系吸收,而较少来源于前期营养体的氮素转移;其淀粉总量、支链淀粉含量较高,而直/支比值较低。在蛋白质及其组分含量上,郑单21含有较高的粗蛋白总量及清蛋白、球蛋白和谷蛋白含量,但醇溶蛋白含量较低;在脂肪酸及其组成上,虽然郑单21的脂肪酸总量较低,但不饱和脂肪酸比例较高。在各品质组分上,支链淀粉、醇溶蛋白、软脂酸、油酸和亚油酸含量对氮肥的反应与淀粉含量、粗蛋白含量和脂肪酸总量的变化趋势基本一致,均随施氮量的增加而增加,但过量施氮则其含量下降。施氮对直链淀粉含量、清蛋白、球蛋白和谷蛋白含量、硬脂酸、花生酸和亚麻酸无明显影响。     

Response of different pomegranate cultivars to foliar application of potassium nitrate in arid irrigated region of Punjab

Ambe-bahar crop response of four pomegranate cultivars to foliar applications of potassium nitrate (0, 0.5, 1.0, and 1.5%) in May–June was evaluated at Punjab Agricultural University Regional Research Station, Abohar, Punjab, India, during 2015 and 2016. The experiment was laid out in randomized block design, replicated thrice. Over control, potassium nitrate significantly improved growth and productivity of pomegranate. Different spray concentrations considerably influenced plant volume in Phule Arakta and Ganesh. The differences in fruit yield were non-significant in Bhagwa and Phule Arakta. In Mridula and Ganesh, maximum yield was noted at 1.5% sprays which, however, were statistically comparable to 1% sprays. Fruit quality also varied markedly with the type of cultivar and concentration of spray solution. From the study, it comes out that potassium nitrate sprays at 0.5% in Bhagwa and Phule Arakta is highly beneficial in maintaining higher productivity and quality of fruits. In Mridula and Ganesh, 1% sprays prove more advantageous.     

Foliar nutrition of baby corn (Zea mays L.)

Abstract

Field experiments were conducted during late Rabi (January to March) and Kharif (June to September) seasons of 2002, to study the influence of foliar spraying of nutrients on growth and yield of baby corn (Zea mays L.). The experiment was laid out in randomized complete block design with three nutrients (phosphorous [P], potassium [K] and boron [B]) each at three concentrations along with control (water spray) and absolute control (no spray). Di-ammonium phosphate, Muriate of Potash and Borax are the sources of P, K and B nutrients respectively. Results showed that spraying of P favorably influenced the growth parameters, yield attributes and green cob and fodder yields of baby corn. Application of P at 0.75% concentration at 25 and 45 days after sowing (DAS) gave significantly higher growth parameters with thicker cobs and corns, increasing the individual cob weight, which in turn increased the green cob yield of baby corn. Increased growth parameters resulted in increased green fodder yield. Application of B and K with different concentrations and P (0.25 and 0.50%) failed to influence the growth and yield of baby corn.     

Tomato growth responses to foliar application of ammonium sulfate in hydroponic culture

This study was done to evaluate the growth responses of tomato plants (Lycopersicon esculentum Mill.) to foliar application of ammonium sulfate in different concentrations of 0, 50, 100, or 200 mM once per week, as well as 50 mM in every other day under greenhouse and hydroponic culture system. The results showed that foliar application of ammonium restricted the plant height, yield, and vitamin C content of fruits, but it increased the chlorophyll content in treated plants. The highest and the lowest yield were obtained from zero (control) and 200 mM treated plants, respectively. Fruit hardness was not affected by treatments, while blossom end rot disorder was increased by higher concentrations of ammonium sulfate. In general, the result indicated that tomato plant is rather sensitive to foliar application of ammonium sulfate particularly to higher concentrations and application numbers.     

降雨量和氮素对黑土区春玉米产量的影响

为了研究在田间旱作农业条件下主要生长因子对玉米产量的影响,采用同一品种春玉米、同一“3414”肥料试验设计方案,在土壤有效氮量中等,有效磷、钾含量均较高的黑土上进行了连续3年的玉米田间试验.结果表明,影响玉米产量的3个主要因素分别是玉米生育期降雨量、氮肥施用量和土壤氮素水平.玉米生育期降雨量对产量的影响最大,生育期降雨量越大,玉米产量越高,二者之间呈正相关关系.只有在生育期降雨大于280 mm的情况下,施用氮肥才有较为明显的增产效果,低于此值,氮肥增产效果不明显.与不施肥相比,施用氮、磷、钾肥平均增加水分利用效率24.3％.玉米产量与播前土壤碱解氮之间旱正比,高水平的土壤碱解氮有利于玉米产量的提高.     

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.     

秸秆还田与施氮对冬小麦生长发育及水肥利用率的影响

田间试验研究了小麦-玉米一年两熟耕作区玉米秸秆还田与氮肥配施和化肥单施对冬小麦生长发育、籽粒产量及氮肥表观利用率和水分利用效率的影响。结果表明, 施氮量相同时, 秸秆与氮肥配施越冬前和拔节期冬小麦总茎数和单株分蘖数低于化肥单施, 施氮量在75~225 kg·hm^-2 时, 植株干重高于化肥单施; 孕穗期到成熟期植株干重、成穗率和产量构成因素秸秆与氮肥配施处理高于化肥单施处理, 籽粒产量增加58.9~339.6kg·hm^-2, 水分生产率提高0.026~0.083 kg·m^-3。施氮量在75 kg·hm^-2 时, 秸秆与氮肥配施的氮肥表观利用率低于化肥单施; 在150~300 kg·hm^-2 时高于化肥单施。因此, 针对目前黄淮海麦区小麦-玉米一年两熟种植制度下, 秸秆还田前期生物争氮、后期供肥能力增强的特点, 秸秆连续还田后配施纯氮225 kg·hm^-2, 可有效提高灌水和氮肥利用率, 实现冬小麦高产高效栽培。     

铜氮配施对冬小麦籽粒产量和蛋白质含量的影响

在豫中潮土区通过田间裂区试验研究了铜、氮配施对冬小麦籽粒产量和蛋白质的影响。结果表明,氮肥对冬小麦籽粒产量和蛋白质产量影响达极显著水平,对蛋白质含量影响不显著。铜肥对籽粒产量和蛋白质产量的影响都达到极显著水平,对籽粒蛋白质含量影响达显著水平。氮、铜交互对冬小麦籽粒产量和蛋白质产量影响达极显著差异,对蛋白质含量影响也达显著差异。综合考虑产量和蛋白质因素,本试验条件下,铜、氮配施以N1Cu2处理(即施氮120 kg.hm-2,施铜45 kg.hm-2)为适宜的铜、氮配施比例。     

Irrigated and rain-fed maize response to different nitrogen fertilizer application methods

With the demand for maize increasing, production has spread into more water limited regions. Couple this with increasing resource costs and environmental concerns and the need for efficient nutrient and water management practices has increased. The objective of this trial was to evaluate the effects of different nitrogen (N) fertilizer application methods and timings on maize grain yield, N use efficiency (NUE), and water use efficiency (WUE) under irrigated and rain-fed conditions. Four site-years of data were collected. Fertilizer treatments consisted of all N applied preplant, split surface applied, and split foliarly applied. Irrigation applied prior to and during reproductive growth increased grain yield, NUE, and WUE compared to rain-fed treatments for all site-years. Split surface applied N fertilizer applications typically increased NUE, but not always grain yield compared to preplant applications. The use of split foliar N fertilizer applications was only beneficial in the site-years when leaf burn was not as severe.     

减量施氮与间作模式对甜玉米AMF侵染和大豆结瘤及作物氮磷吸收的影响

通过4季(2014年秋季,2015年春、秋,2016年春季)大田定位试验,对比研究了两种施氮水平[300 kg·hm~(-2)(N1:减量施氮)和360 kg·hm~(-2)(N2:常规施氮)]和4种种植模式[甜玉米|菜用大豆2∶3(S2B3)、2∶4(S2B4)间作、甜玉米单作(SS)和菜用大豆单作(SB)]对华南地区甜玉米和大豆产量、甜玉米AMF侵染率、大豆根瘤菌等的影响。结果表明,减量施氮间作处理的甜玉米产量显著高于单作。2016年春季S2B3-N1处理大豆的根瘤数显著高于S2B3-N2处理;4季减量施氮和间作处理对大豆根瘤干重均没有显著影响。2015年春秋两季两种施氮水平间作处理的甜玉米生物量和氮含量均显著高于相应的单作处理;且减量施氮间作模式甜玉米AMF侵染率显著高于常规施氮处理。2015年秋季减量施氮间作模式处理甜玉米的磷含量显著高于单作处理。减量施氮与间作菜用大豆显著提高了甜玉米氮和磷含量、AMF侵染率、生物量及产量,是华南地区甜玉米资源高效利用的可持续生产模式。     

Efficiency of foliar selenium application on oilseed rape (Brassica napus L.) as influenced by rainfall and soil characteristics

The Czech Republic is characterized by a low Se soil content, resulting in Se deficiency in crops, humans, and animals. This study investigated the response of oilseed rape to foliar application of selenate solution in a microscale field experiment conducted at two locations differing in soil and climatic conditions but with comparable total Se contents. Sodium selenate (Na₂SeO₄) was applied at two rates (25 and 50 g Se ha^?1). The potential effect of Se application on the uptake of essential elements was also evaluated. The foliar Se application resulted in an effective stepwise increase in the Se contents of all the plant components studied (leaves > stems > roots > siliques ~ seeds), as expected. No significant influence of Se fortification on the other investigated macro- and microelements was observed. However, the soil and climatic conditions influenced the Se uptake, such that a higher Se content was observed in plants grown in the most acidic location (Cambisol soil) that had a higher oxidizable carbon content and higher average annual rainfall compared to the less acidic location (Luvisol soil). These observations indicated the necessity to optimize the Se application for the particular soil and climatic conditions to achieve a maximum biofortification effect.     

Effect of phosphorus,nitrogen fertilization and foliar applied manganese on yield and nutrient concentration of soybean

Abstract

A greenhouse experiment was conducted on clay loam soil of pH 7.8 to evaluate the effect of P, N fertilization and foliar applied Mn on yield and nutrient concentration in leaves and seeds of soybean. A significant yield increase was obtained for each added increment of P fertilizer up to 30 kg P₂O₅/acre. At application rates of 0, 15, 30 & 45 kg P₂O₅/acre, the seed yield was subsequently 27.8, 65.8, 82.8 & 83.6% of the maximum yield obtained at the maximum calculated P level. The yield increase accounted 14.2 and 10.2% for N and Mn applications. In all treatments, in which P was combined with N, the seed yield was relatively higher than with P or N applied alone.

Phosphorus, N and Mn content in leaves and seeds were positively correlated with the applied nutrient fertilizers. At any given level of applied P and Mn, P content was significantly higher in +N than ‐N treatments. By Mn application, P content in leaves and seeds was decreased. Phosphorus and Mn applications did not influence N content in leaves and seeds.     

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。     

施氮量对潮土区冬小麦-夏玉米轮作农田氮磷淋溶的影响

潮土是我国华北地区主要土壤类型之一,潮土区是我国冬小麦-夏玉米作物的主要产区,研究不同施氮量潮土氮磷淋溶特征对于指导区域农田面源污染防控具有重要意义。本研究设置3个施肥处理,即传统施氮(CON)、优化施氮(OPT)和优化再减氮(OPTJ),利用田间渗漏池法,研究潮土冬小麦-夏玉米轮作农田硝态氮及总磷淋溶特征。结果表明:2016—2018年,冬小麦-夏玉米轮作周年不同施肥处理90cm土层年淋溶水量79.0～102.5 mm,不同淋溶事件间土壤淋溶液硝态氮浓度波动较大, CON、OPT和OPTJ处理单次淋溶事件硝态氮浓度分别为18.9～208.7(平均为72.7) mg·L~(-1)、9.0～99.2 (平均为33.8) mg·L~(-1)、4.7～55.5 (平均为15.4) mg·L~(-1)。本研究区域冬小麦-夏玉米轮作模式的氮素淋溶风险较高,磷素淋溶风险较低。传统施氮处理(CON)下农田硝态氮的平均淋溶量和表观淋失系数分别为66.4 kg·hm~(-2)和10.3%,而总磷(TP)为0.06 kg·hm~(-2)和0.04%。氮肥减施会显著降低氮素淋失,OPT和OPTJ处理的氮素淋溶减排率可达56.3%和78.9%。两个年度CON、OPT和OPTJ处理硝态氮平均表观淋失系数分别为10.3%、6.2%和4.9%,随着施氮量的增加,硝态氮淋失系数动态增加。氮淋溶具有较大的年际变化,降雨量高的2018年比降雨少的2017年硝态氮淋溶量多57.0%。两个年度CON、OPT和OPTJ处理总磷平均淋溶量分别为0.06 kg·hm~(-2)、0.06 kg·hm~(-2)和0.08 kg·hm~(-2)。适量减施氮肥会增加作物产量, OPT处理的作物产量是CON处理的1.08倍。然而,过量减施则会带来减产风险, OPTJ处理氮肥减施56%,作物产量比CON处理降低2.0%～8.1%。总之,潮土区农田硝态氮淋溶风险较大,适量减施氮肥能够在保证作物产量的基础上显著降低氮素淋失损失。     

潮土小麦碳氮含量对长期不同施肥模式的响应

【目的】以潮土21年长期定位试验为基础,分析不同施肥模式下冬小麦不同生育期的地上部生物量、碳氮含量、碳氮比及碳氮积累量,探讨冬小麦碳氮含量对不同施肥模式的响应规律。【方法】试验包括不施肥(CK)、单施氮肥(N)、施氮磷肥(NP)、施氮钾肥(NK)、氮磷钾配施(NPK)、氮磷钾肥配施有机肥(NPKM)、施氮磷钾肥及玉米秸秆还田(NPKS)7个处理。在2011 2012年冬小麦生长季,分别采集越冬、拔节、灌浆、成熟四个生育时期地上部植株样品,利用Euro Vector EA3000型元素分析仪对小麦植株样品的全碳、全氮含量进行测定。【结果】NPK、NPKM和NPKS处理均能显著提高各生育期小麦地上部干重,其中NPKM处理小麦地上部干重在越冬、拔节、灌浆、成熟期分别比CK提高了111%、194%、238%、206%,除越冬期外,等量氮肥条件下,NPK、NPKM和NPKS 3个处理间小麦同一生育期地上部干重无显著差异,说明与氮磷钾配施相比,有机无机配施与秸秆还田这两种措施并不能显著提高小麦地上部生物量;小麦地上部碳含量受不同施肥影响很小,不同生育期小麦地上部碳含量平均值为410 g/kg;小麦成熟期地上部氮含量以N和NK处理最高,分别达到19.4和18.1 g/kg,其中N处理小麦地上部氮含量分别比NPKM和NPKS处理高52%和66%。随着生育期的推移,各处理小麦氮含量逐渐降低,总体表现为越冬期拔节期灌浆期≥成熟期;在整个生育期中各施肥处理碳含量基本保持不变而氮含量呈逐渐下降趋势,这就使得各施肥处理地上部分C/N比随生育期的推移呈逐渐增加趋势;不同施肥下小麦碳积累量差异性和地上部干物质重差异性规律一致,而不同施肥下地上部氮积累量差异性不同于干物质重的差异性,以NP处理最高,达545 kg/hm2,分别比NPKM和NPKS处理高61%和68%。【结论】施肥方式不能显著改变小麦碳含量但能影响氮含量,因此小麦生物量大小决定了其碳的积累量,相应地,C/N比大小则由氮含量决定。氮磷钾配施、有机无机配施及秸秆还田处理下,小麦具有较高的生物量从而具有较高的碳氮积累量,这有利于增加农田系统碳、氮积累,提升土壤碳、氮肥力。