长期施氮、磷、钾化肥对玉米产量及土壤肥力的影响

以1990年建立的国家褐潮土土壤肥力与肥料效益长期监测基地(北京昌平站)的长期肥料定位试验为研究平台,研究了不同施肥制度对玉米产量和土壤肥力的影响。结果表明,长期均衡地施NPK肥或NPK与有机肥配施,可以显著提高玉米产量和土壤有机质、全氮、全磷、速效氮、速效磷、速效钾等肥力指标,并能提高土壤微量元素的含量;而不均衡施肥(N、NK、NP、PK)导致相应的营养元素的耗竭。相关分析表明,在褐潮土上增施磷肥和有机肥对提高玉米产量具有重要的作用。     

Response of maize to nitrogen,phosphorus, and potassium fertilizers in the savanna zones of Nigeria

Abstract

Field trials were conducted for three years on the response of maize to nitrogen (N), phosphorus (P), and potassium (K) fertilizers on Oyo Soil Series (Arenic Haplustalf) and Iregun series (Aquic Haplustalf) in the derived savanna and southern guinea savanna zones of Nigeria, respectively. Nitrogen fertilizer as granulated urea at rates 0–300 kg N/ha, P fertilizer as single superphosphate at rates 0–120 kg P/h, and K fertilizer as muriate of potash at rates 0–180 kg K/ha were used for the different nutrient combinations. The base rates for N, P, and K were 100 kg N/ha, 40 kg P/ha, and 60 kg K/ha, respectively. The results of the trials showed that annual application of the blanket recommended N, P, and K rates to maize grown under intensive land use system could not produce optimum yield. Fertilizer efficiency varied along with soil test values from year to year. The highest response by maize in these zones was to N, the optimum rate ranged from 50–100 kg N/ha. Application of high rates of P and K fertilizers on soils with fairly sufficient nutrient level showed no significant effect on maize yield. But when P and K were applied at low rates (20 kg P/ha and 30 kg K/ha), their contents in the leaf and maize yield, in most cases, increased significantly. The results, however, showed that N, P, and K recommendations for optimum maize yield in both zones are 50–100 kg N/ha, 20 kg P/ha, and 0–30 kg K/ha, respectively.     

Nitrogen recovery by orchardgrass from dairy manure applied with or without fertilizer nitrogen

Abstract

With increasing manure production per unit cropland available for its disposal, greater recovery and recycling of manure nitrogen (N) through crop uptake is needed on dairy farms to minimize environmental problems. This study was conducted in 1990 and 1991 on a sandy loam soil with the objective of quantifyin forage yield and N recovery by orchardgrass (Dactylis glomerata L.) in response to dairy manure applied in spring with or without fertilizer N. Manure N, either as liquid or as solid with bedding, was surface applied annually to supply 150 kg total N/ha/yr with four rates of fertilizer N (0, 75, 150, and 300 kg N/ha in 1990 and 0, 150, 300, and 600 kg N/ha in 1991) factorially superimposed over the manure treatments. Averaged over years, orchardgrass recovered 40% of the liquid manure N and 26% of the solid manure N applied each year. On an annual basis, the crop recovered 430 kg soil N/ha/yr from plots receiving liquid manure in combination with 600 kg fertilizer N/ha. This study demonstrates that intensively managed orchardgrass has the potential to absorb large quantities of manure N.     

Effects of repeated straw incorporation on crop fertilizer nitrogen requirements, soil mineral nitrogen and nitrate leaching losses

Abstract. The effects of straw disposal by burning and incorporation on soil and crop nitrogen (N) supply, were investigated on two light textured soils in central (ADAS Gleadthorpe) and eastern England (Morley Research Centre) over the period 1984 to 1995. Nitrogen balance calculations showed that after 11 years of contrasting straw incorporation versus burn treatments, the cumulative N returns in straw were c . 570kg/ha at Gleadthorpe and c . 330 kg/ha at Morley However, these N returns via straw incorporation were not reflected in increased total soil N levels in autumn 1994. There were no differences ( P > 0.05) between straw disposal treatments in autumn soil mineral N supply, readily mineralizable N or organic carbon. Similarly, there were no consistent differences between the treatments in terms of crop yield, crop N uptake or optimum fertilizer N rates. Fertilizer N applications of 200 kg N/ha/y increased topsoil organic carbon from 1.18 to 1.28% and total N content from 0.091 to 0.102% on the loamy sand textured soil at ADAS Gleadthorpe, but not at Morley. Previous fertilizer N applications increased the quantity of nitrate-N leached in drainage water by c . 20 kg/ha at Gleadthorpe and c . 60 kg/ha at Morley overwinter 1994/95, and by 10–20 kg/ha at both sites overwinter 1995/96. There was some indication overwinter 1994/95 that straw incorporation reduced nitrate-N leaching by 10–25 kg/ha, but there were no differences between treatments overwinter 1995/96.     

长期不均衡施肥对紫色土肥力质量的影响

利用长期定位试验研究了不均衡施肥对紫色土土壤肥力、肥料利用率和养分平衡状况的影响。结果表明,连续11年不施肥,耕层土壤有机质和全氮含量降低,施用化肥的各个处理土壤有机质和氮素含量稳中有升,其中以NPK均衡施用增幅最大。所有施磷处理,土壤速效磷含量与试验前相比都有大幅度提高;无论施钾与否,土壤缓效钾含量均比试验前降低,稻草还田土壤缓效钾下降最少。不均衡施肥降低了肥料利用率和肥料的增产效果。每季施N.150kg/hm2,维持了土壤氮素肥力;每季施P2O560～75.kg/hm2,磷素都有赢余;除秸秆还田处理钾素有盈余外,其余各处理钾都亏缺。     

长期稻草还田对紫色水稻土肥力和生产力的影响

通过8年淹水条件下一季中稻的田间定位试验,研究了长期稻草还田以及稻草与不同化肥配合施用对紫色水稻土生产力和土壤肥力的影响。结果表明,稻草与N、P、K化肥配合施用能维持或提高紫色水稻土的生产力和土壤肥力;水稻获得了持续高产,土壤有机质和全氮含量提高,土壤磷的有效性增加,速效钾与试验前基本平衡。纯化肥处理尤其是N、NP、NK处理水稻产量、土壤氮和钾含量逐年降低,不能维持系统生产力和土壤肥力。稻草还田对翌年水稻具有显著的增产作用,8年平均稻草还田处理比对照增产39.5%,稻草的增产作用还随着稻草还田时间的延长而逐年升高。稻草还田携入的钾与化学钾肥具有相同的营养功效,稻草可替代部分化学钾肥。     

日光温室番茄氮素资源综合管理技术研究

根据养分资源综合管理原理,应用氮素供应目标值结合PSNT(Presidedress.Soil.Nitrate.Testing)技术对日光温室春、秋季番茄主要生育时期0—30.cm土壤硝态氮进行实时监测并进行氮素追施调控。试验设计为:当春季目标产量为84.t/hm2时,在第一、二、三穗果膨大期每次追肥时采用N.300.kg/hm2的氮素供应目标值(0—30.cm土层NO3--N+灌溉水带入氮素+追施化肥氮素),之后每次追肥采用N.200.kg/hm2的氮素供应目标值;当秋季目标产量为75.t/hm2时,在第一、二、三、四穗果膨大期每次追肥时采用N.200.kg/hm2的氮素供应目标值,之后每次追肥采用N250.kg/hm2的氮素供应目标值。结果表明,与传统氮素处理相比,由于充分利用了来自环境的氮素养分(包括矿化态有机氮和灌溉水中氮素),氮素追施调控处理的番茄在春季生长后期(3至6穗果生长时期)、秋季生长前期(1至3穗果生长时期)没有追施氮肥;在氮肥总投入量分别减少62%和78%的情况下,番茄产量不降低,但显著降低了土壤—蔬菜体系中氮素表观损失量,作到了氮素资源的综合管理与作物的高效利用,减轻了过量施氮对环境产生的负面影响。     

Effets des engrais N,P et K sur le rendement et la qualite de l'ensilage ue mais

Abstract

Thirteen fertility trials were made throughout Quebec's corn growing region during 1972–74. These included eleven fertilizer combinations with corn silage as the test crop and were carried out on nine soils. Total dry matter and digestible nutrients (TDN) varied greatly from year to year, though, mean yields increased by 23 and 30 percent respectively with the 50 kg N/ha treatment, compared to control receiving no nitrogen fertilization. However, 150 kg N/ha was required to attain a maximum yield of 1250 kg/ha crude protein. Despite a 0.2 percent nitrate content found in the silage grown on the most northerly site, a 120 kg P/ha combined with 100 kg N and K gave the highest mean TDN production (9580 kg/ha).

Potassium fertilization affected plant K content of corn grown at the most northerly site only, where a 0.5 percent was found with the control on a suit containing low potassium levels. Further, striking increases in Ca and Mg concentrations were observed with corn grown on that soil. However, magnesium concentration ranging from 0.11 to 0.14 percent were found with nine field trials out of twelve. Also, low K:(Ca + Mg) ratios were found on three trials, which were increased with potassium fertilization levels of 150 kg K/ha. Accordingly, it is suggested that uptakes of 200, 48, 200, 30 and 30 kg/ha of N, P, K, Ca and Mg are required for good corn silage crops.     

基于土壤氮素平衡的旱地冬小麦监控施氮

提高作物产量,平衡土壤氮素携出,培肥土壤,避免过多肥料氮残留造成淋溶,是旱地作物施氮的主要目标。本研究通过1 m土层硝态氮监控,从土壤氮素的输入和携出平衡计算氮肥用量,并在陕西永寿不同肥力水平的地块上连续2年布置田间试验进行验证。结果表明,与习惯施肥相比,监控施肥的氮肥用量减少41.2%,籽粒平均增产17.0%,氮肥偏生产力平均增加188.3%,产投比平均提高28.9%。监控施肥处理在收获期1 m土层硝态氮残留量平均为37.0 kg/hm2,较习惯施肥（112.1 kg/hm2）降低66.9%。经过降雨集中的夏季休闲期后,监控施肥处理1 m土层的硝态氮平均增加15.4 kg/hm2,习惯施肥则减少27.4 kg/hm2。这说明通过对1 m土层硝态氮的监控,依据土壤养分平衡,计算旱地小麦氮肥用量,可以提高产量,有效减少氮肥投入,降低成本,增加农户收入,提高氮肥效率,减少旱地土壤硝态氮残留和淋溶。     

Comparative evaluation of broiler and layer poultry manure for greenhouse lettuce production

Abstract

Disposing poultry manure from broiler and layer flocks by its incorporation into the soil was evaluated on greenhouse lettuce (Lactuca sativa L. cv. Paris Island cos). Floor litter that contains the manure mixed with sawdust and wood shaving, was 8 weeks old from broilers and one year old from layers. Broiler manure had 19% moisture and 5.5% N, while layer manure had 22% moisture and 3.7% N. Application of 27.5 ton/ha broiler manure and 18 ton/ha layer manure, on wet basis, gave comparable yield of lettuce as did an application of 100 kg N/ha from NH₄NO₃ in 2 split applications, and an unfertilized treatment. The manure was effective for lettuce growth 10 months after its incorporation in the soil. The highest yield was in manure treated plots, however, the lack of significant response in yield is due to the sufficient levels of soil NO₃‐N and available P. There was no effect on soil EC, pH, and available P due to the treatments; however, soil NO3‐N was significantly increased under all fertilized treatments. Leaf concentration of PO4‐P was not affected by the treatments, but NO3‐N was significantly increased under all fertilized treatments. It may be concluded that broiler and layer poultry manure when disposed of by soil incorporation, are equally effective as a fertilizer for a leafy crop such as lettuce.     

Dryland corn response to tillage and nitrogen fertilization. I. Growth‐yield‐N relationships

Abstract

Crop response to fertilizer nitrogen (N) is dependent upon tillage management. This study was conducted to determine how tillage rotation influences non‐irrigated crop growth, N uptake and yield. The effects of tillage rotation, N rate and N timing schedule on early season dry matter production and N uptake, ear leaf N concentration at silking, and yield of corn [Zea mays (L.) Pioneer 3378] were investigated at Painter, VA, on an Altavista loam (fine‐loamy, mixed, thermic Aquic Hapludult). In 1986, maximum yields achieved in the 6‐year continuous no till (NT) [5.82 Mg/ha] and first year no till (AT) [5.64 Mg/ha] were significantly greater than that of the 6‐year continuous conventional till (CT) [3.67 Mg/ha], but no yield differences were obtained in the drier 1987 season. A higher rate of N fertilizer was required to obtain maximum yield in the first year no till (168 kg N/ha) than in the NT (112 kg N/ha) during 1986. Early 1986 N uptake and growth response with and without N at planting increased in the order CT < AT = NT and AT < CT < NT, respectively, indicating greatest immobilization of soil N occurred in the newly established no till soil. Lack of differences in critical ear leaf N values developed for NT and CT in each year imply that plant norms developed for one tillage system may accurately assess N status of corn grown under different tillage practices.     

Layer and broiler poultry manure as nitrogen fertilizer sources for cabbage production

Abstract

Floor litter from one‐year‐old laying hens (LHM) and from eight‐week‐old broiler chickens (BCM) were incorporated in the soil of two fields and evaluated as nitrogen (N) sources for cabbage production on a non nutrient‐depleted soil. LHM had 3.4% moisture, 3.84% N and 3.41% phosphorus (P). BCM had 2.3% moisture, 4.46% N and 2.19% P. Field 1 recieved 2.4 t/ha BCM, 3.0 t/ha LHM, whereas Field 2 recieved 4.8 t/ha BCM and 6.1 t/ha LHM. Also, each field received ammonium sulfate [(NH₄)₂SO₄] at a N rate of 100 kg/ha and an unfertilized control treatment. The manure was applied one week before cabbage transplanting on 18 May 1992. Ammonium sulfate was applied in two equal split applications during the growing season. Leaf nitrate‐nitrogen (NO₃‐N) was higher at harvest in plants receiving the higher manure rate than in other treatments (P<0.05). Leaf phosphate (PO₄‐P) was higher in early season in plants receiving LHM at both Tates than in other treatments. Soil BD, EC, NO₃‐N, and P at harvest were not affected by the treatments (P>0.05). Soil pH was reduced by the LHM in comparison to other treatments (P<0.05). Yield was comparable among all treatments (P>0.05) . It may be concluded that low application rates of LHM and BCM are equally effective in supplying the N requirements of cabbage, with BCM recommended when only N is limiting, and LHM when P is limiting.     

长期水稻-大麦轮作体系土壤供氮能力与作物需氮量研究

通过18年稻麦轮作,7个施肥处理,研究了水稻-大麦轮作系统中土壤生产力、氮素自然供应能力、作物氮素内部利用率及氮肥表观利用率。结果表明,在水旱轮作下,土壤对大麦产量的地力贡献率平均为69%,水稻为75%～81%; 肥料的增产贡献率分别为31%和19%～25%,可维持每年生产大麦2.3 t/hm2、稻谷6～7 t/hm2。土壤氮素自然供给力在大麦上平均为75.9%,比水稻的低3.3%～7.2%。在一年三熟水旱轮作制中,土壤和环境年供氮118～299 kg/hm2; 在一年二熟轮作制中为86～199 kg/hm2。施氮肥条件下,大麦的氮素内部利用率为31.0～56.3 kg/kg; 水稻在23.6～50.2 kg/kg之间变动; 大麦的氮肥利用率变幅在27.5%～41.2%,水稻为14.6%～41.2%。在稻麦轮作系统中,如果想获得作物产量12 t/hm2（4 t大麦和8 t 单季稻）,需要每年施氮肥 N 226～337 kg/hm2。为获得更高的作物产量,在氮肥推荐时不但要考虑作物的目标产量,作物对氮素的需要量,还要充分考虑土壤和环境氮素供应能力。     

Effects of biochar,urea and their co‐application on nitrogen mineralization in soil and growth of Chinese cabbage

Experiments were conducted to study the effect of soil applications of kunai grass (Imperata cylindrica) biochar (0 and 10 t/ha) and laboratory grade urea (0, 200 and 500 kg N/ha) and their co‐application on nitrogen (N) mineralization in an acid soil. The results of an incubation study showed that the biochar only treatment and co‐application with urea at 200 kg N/ha could impede transformation of urea to ammonium‐N (NH₄⁺‐N). Soil application of biochar together with urea at 500 kg N/ha produced the highest nitrate‐N (NO₃^?‐N) and mineral N concentrations in the soil over 90 days. Co‐application of urea N with biochar improved soil N mineralization parameters such as mineralization potential (N_A) and coefficient of mineralization rate (k) compared to biochar alone. In a parallel study performed under greenhouse conditions, Chinese cabbage (Brassica rapa L. ssp. chinensis L.) showed significantly greater (P < 0.05) marketable fresh weight, dry matter production and N uptake in soil receiving urea N at 500 kg/ha or co‐application of biochar with urea N compared to the control. Application of biochar only or urea only at 200 kg N/ha did not offer any short‐term agronomic advantages. The N use efficiency of the crop remained unaffected by the fertilizer regimes. Applications of biochar only at 10 t/ha did not offer benefits in this tropical acid soil unless co‐applied with sufficient urea N.     

The influence of sub-optimal irrigation and drought on crop yield, N uptake and risk of N leaching from sugarbeet

Abstract. Variously timed sub-optimal irrigation strategies were applied to sugarbeet grown on a light soil (loamy sand or sandy loam) over four seasons (1991 to 1994) to investigate the effect on crop growth and nitrate leaching risk. Data from the two dry seasons, (1991 and 1994) are reported here. In the driest year (1991) soil mineral N levels after autumn harvest were negatively related to crop water use ( P < 0.05). In this season, there was little drainage from the soil profile, and full irrigation reduced residual soil N by 31 kg N/ha (0-90 cm) compared with the unirrigated treatment (79 kg N/ha). The potential for N leaching during the ensuing winter was consequently more than halved. In 1991 and 1994 there was a strong positive linear relationship between dry matter yield, N uptake and water use, but a negative relationship between plant N concentration and water use. These relationships were a function of the severity and not the timing of drought. The additional N uptake associated with increased irrigation and crop water use was biased towards a large concentration in the aboveground crop (tops), which are normally returned to the soil. The C:N ratio of sugarbeet tops was affected by crop water supply with droughted crops having lower values. This would also influence N release and subsequent leaching risk. However, the effects of drought on N leaching risk were relatively small when compared with other root crops such as potatoes.     

The Effect of MSW Compost on Metal Uptake and Yield Of Wheat,Barley and Canola in Less Productive Farming Soils of Alberta

Experiments were started in May 1998 at two sites to measure various crop responses to a mixed municipal solid waste-biosolids cocompost (named Nutri Plus) and examine the fate of certain metals associated with Nutri Plus compost. There were six treatments: Check, 50, 100, and 200 T compost/ha, NPKS (75 kg nitrogen (N) /ha, 20 kg phosphorus (P)/ha, 45 kg potassium (K) and 18 kg sulphur (S)/ha), PK (20 kg P, 45 kg K/ha), and three crops: canola (Brassica rapa cv. ‘Hysyn 110’), wheat (Triticum aestivum L. cv. ‘Roblin’) and barley (Hordeum vulgare L. cv. ‘Lacombe’). Each treatment was replicated four times and was in a complete randomized block design. In the compost treatments, 20 kg P and 45 kg K were applied due to low concentration of these two nutrients in the compost. Soil and plant samples were analyzed for nutrient content such as N, P and K. In addition, plant samples and soil samples after the compost application were also analyzed for elemental content of As, B, Cr, Co, Cu, Zn Se, Mo, Cd, Hg and Pb. The research results show that the compost slightly increased heavy metal concentrations in the soil but did not cause any phytoxicity to crops. Yield from 100 and 200 T/ha application was higher with the compost than with NPKS treatment. However, the yield of the 50 T/ha application was similar to that of NPKS treatment. Comparing the two sites, the compost apparently was more beneficial at Site 1 than at Site 2 in the year of application. This is likely due to the lower indigenous soil fertility and poor soil physical properties at Site 1. The N content in cereal grains was similar among the compost treatments but lower than the Check and NPKS treatments due to the diluting effect of higher yield. The oil content in canola seed was similar among all treatments. The results suggest that Nutri Plus compost applications generated positive yield responses in all three crops. Crop yield increased as the application rate increased. Heavy metal loading was not an immediate problem with the compost application, although it will limit total compost application over time to the same soil     

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。     

长期施肥条件下华北平原农田硝态氮淋失风险的研究

利用河北辛集潮土(21年)和北京昌平褐潮土(9年)两个长期定位施肥试验研究了华北平原冬小麦夏玉米轮作体系下农田氮素平衡和硝态氮淋失风险。结果表明,单施氮肥的增产效果有限,昌平试验点甚至出现减产现象;而适量有机肥与氮磷或氮磷钾配施可显著提高作物产量,降低氮素盈余。单施氮肥时,辛集和昌平土壤硝态氮峰值分别达20.7和30.0.mg/kg,出现在160200.cm和90120.cm土层;硝态氮累积量高且大部分集中在根区外土壤,硝态氮淋失风险大。氮磷或氮磷钾肥配施时,硝态氮峰值出现深度上移3040cm,根区和根区外土壤硝态氮累积量均大幅降低,淋失风险明显减弱;在氮磷或氮磷钾肥基础上适量施用有机肥时,硝态氮峰值出现深度进一步上移至根区土壤,深层土壤硝态氮累积量显著下降,淋失风险低。过量施用有机肥或过量施用氮肥时,深层土壤硝态氮累积量大幅增加,甚至超过单施氮肥处理,淋失风险大大增强。研究结果表明,氮磷钾肥与有机肥配合施用是提高作物产量、控制农田硝态氮淋失的重要途径。     

长期肥料定位试验栗钙土中磷肥在莜麦上的产量效应及行为研究

研究了高寒半干旱区8年肥料定位试验中,磷肥和有机肥在莜麦上的产量效应、土壤磷素的平衡、土壤Olsen-P及各形态无机磷的变化。结果表明,单施磷肥(N0P1)莜麦增产30.8%、单施氮肥(N1P0)增产109.4%、氮肥和磷肥配合(N1P1)施用莜麦增产314.0%;NP间表现出显著正交互作用,NP(N1和P1)交互作用增产86.9%;施用22.5和45.0.t/hm2有机肥分别比N0P0处理增产115.1%和220.1%;施用有机肥基础上增施磷肥无明显增产效应。不同施肥处理土壤Olsen-P和各形态无机磷的增减取决于土壤磷素的积累与消耗量,7年不施磷肥土壤Olsen-P降低3.3mg/kg。施用磷肥和有机肥土壤各形态磷库均有不同程度的积累;土壤磷素积累以无机磷为主,其中Ca2-P和Ca8-P的积累量分别占土壤无机磷变化总量的19.3%和25.4%,Al-P和Fe-P分别占23.8%和14.8%,O-P和Ca10-P共占13.0%。依据土壤磷素收支平衡状况计算出维持土壤磷素平衡的P2O5用量为45.0.kg/hm2。根据肥料效应函数计算出有机肥用量为0、22.5.t/hm2时,P2O5的最高产量用量分别为98.4.kg/hm2和87.4.kg/hm2。     

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。