Effects of mulching methods on soil nutrient apparent balance under wheat-potato rotation system in the rain-fed area
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摘要:目的
通过研究陇中旱地不同覆盖方式下土壤养分表观平衡状况及其与土壤养分之间的关系,探索适于陇中地区的覆盖模式,为减少化肥投入、提高农民收入和农业可持续发展提供依据。
方法2022—2023年在甘肃省农业科学院定西试验站开展田间试验,采用单因素随机区组设计,种植制度为马铃薯−小麦轮作。设无覆盖对照(CK)、地膜覆盖(PM)、秸秆碎秆覆盖还田(SR)、秸秆带状覆盖还田(SM) 4个处理,采集两年成熟期马铃薯和小麦的植株和土壤样品进行分析。
结果与CK相比,PM、SR和SM 3种覆盖措施提高了马铃薯和小麦植株氮、磷、钾积累量,以PM处理效果最佳,马铃薯植株中氮、磷、钾积累量增幅分别为41.44%、71.99%、49.78%,小麦植株中增幅分别为38.37%、59.70%、64.59%。SR和SM处理提高了土壤中速效养分含量,SR处理的提升效果大于SM处理,该处理下马铃薯季0—20 cm土层土壤碱解氮、速效磷、速效钾含量分别提高了39.31%、14.99%、25.92%,20—40 cm土层土壤速效磷和速效钾含量分别提高了31.97%和15.72%。在小麦季,0—20 cm土层土壤碱解氮和速效钾含量分别提高了21.36%和21.16%,20—40 cm土层土壤速效磷和速效钾含量分别提高了12.03%和14.29%,40—60 cm土层土壤速效磷和速效钾含量分别提高了39.46%和30.67%。CK处理两年土壤养分表观平衡均为氮、磷大量盈余,钾素亏缺。与CK相比,PM处理N、P盈余量分别显著降低了37.38%和27.30%,钾亏缺量增加了60.73%,氮、磷、钾实际平衡率分别为48.0%、106.3%、−94.1%;SR处理氮、磷盈余量分别增加了89.97%和43.75%,钾亏缺量减少了88.18%,实际平衡率分别为159.5%、241.3%、−7.2%;SM处理氮、磷、钾盈余量分别增长了99.19%、46.27%、120.12%,实际平衡率分别为180.6%、255.7%、16.0%。
结论陇中旱地农田现有施肥量和管理措施下,土壤养分表观平衡均表现为氮磷盈余、钾亏缺。地膜覆盖可有效提高作物养分积累量和粗蛋白产量,降低氮磷盈余量,但加剧钾素亏缺。秸秆碎秆覆盖还田和秸秆带状覆盖还田增加作物养分吸收量和粗蛋白产量的效果虽低于地膜覆盖,并加剧了土壤氮磷盈余量,但缓解了钾素的亏缺量。因此,陇中旱地农田长期采用秸秆覆盖措施时应考虑降低氮、磷肥的施用量,采用地膜覆盖措施时应注意提高钾肥的施用量。
Abstract:ObjectivesWe studied the apparent balance of soil nutrients under different mulching methods in dryland of central Gansu, to provide a scientific basis for nutrient management under mulching cultivation.
MethodsA field experiment was carried out at Dingxi Experimental Station of Gansu Academy of Agricultural Sciences in 2022 and 2023, where the planting system was one crop each year under potato and wheat rotation. The experiment was composed of four treatments: no mulching control (CK), plastic film full mulching (PM), crushed straw mulching and returning to field (SR), and whole straw mulching on strip and returning to field (SM). Potato and wheat samples were collected at harvesting stages for analysis of biomass, nutrient contents. Soil samples were collected at the same time for measurement of available nutrient contents.
ResultsCompared with CK, all the PM, SR and SM treatments increased the absorption of N, P, and K by potato and wheat, and PM treatment was recorded the highest absorption with the increment of N, P, and K in potato plants by 41.44%, 71.99% and 49.78%, and in wheat plants by 38.37%, 59.70% and 64.59%, respectively. Both SR and SM treatments increased the soil available nutrient contents, and improvement effect in SR treatment was greater than that of SM treatment. In potato season, SR treatment increased available N, P and K in 0−20 cm soil layer by 39.31%, 14.99% and 25.92%, respectively, and increased available P and K in 20−40 cm soil layer by 31.97% and 15.72%, respectively, and in wheat season, increased 0−20 cm soil layer available N and K by 21.36% and 21.16%, increased 20−40 cm soil layer available P and K by 12.03% and 14.29%, increased 40−60 cm soil layer available P and K by 39.46% and 30.67%, respectively. In CK treatment, the apparent balances of soil N and P were in surplus, and that of K was in deficit in two rotation seasons. PM treatment significantly reduced soil N and P surplus by 37.38% and 27.30%, but exaggerated the K deficit by 60.73%, with the actual balance rate of N, P, and K at 48.0%, 106.3%, and −94.1%, respectively. The apparent N and P surpluses of SR treatment were 89.97% and 43.75% higher than CK, while the K deficit was 88.18% lower than CK, with the actual balance rates of N, P, and K at 159.5%, 241.3%, and −7.2%. The apparent N, P, and K of SM treatment were all in surplus, which were 99.19%, 46.27%, and 120.12% higher than CK, with the actual balance rate of 180.6%, 255.7%, and 16.0%.
ConclusionsThe apparent balance of soil N, and P were in heavily surplus, while that of K was in deficit under the local nutrient management in the potato-wheat rotation system in dryland farmland of central Gansu. Plastic film mulching effectively decreases the P and P surplus but exaggerate the unbalance of K. Straw mulching in full and strip pattern could increase the absorption of N, P and K by crops, the crude protein yield of crops, in spite of that, they still increase the N and P surplus, and alleviates the deficiency of potassium. Therefore, the long-term use of straw mulching in dryland farmland in central Gansu should consider reducing the application rate of nitrogen and phosphorus fertilizer, and plastic film mulching should pay attention to increasing the application rate of potassium.
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土壤养分平衡对作物的增产稳产具有关键作用,同时与农业生态环境密切相关[1]。在农田生态系统中,养分投入和携出之间的差异能够反映土壤养分盈亏状况,养分盈亏率在正负10%之间,视为养分平衡,养分盈亏率小于−10%为养分亏缺,大于10%,为养分盈余[2]。氮素盈余超过20%时,对环境产生潜在威胁[3]。与氮肥不同的是,磷肥后效较高[4],土壤中盈余的磷可以提高土壤的供磷潜力,但肥料磷素的积累仍存在一定的风险[5]。秸秆还田可以增加土壤氮、磷储量,培肥土壤[6]。张新明等[7]研究表明,稻草覆盖可以为土壤提供大量养分且以钾居多,每覆盖还田100 kg稻草可为土壤提供N 0.42 kg、P2O5 0.14 kg、K2O 1.70 kg。张姗等[8]发现水稻秸秆还田后氮素盈余量增加,国内外诸多学者计算了磷平衡与土壤有效磷的定量关系,土壤中每盈余100 kg/hm2的磷可以增加2~5 mg/kg速效磷含量[9]。
位于甘肃中部的定西市是典型的半干旱雨养农业区,全年蒸发量大,降水量少且分布不均,农业生态系统稳定性较差[10],农业生产中常采用地表覆盖方式减少土壤水分的无效蒸发,地膜和秸秆是该地区主要的两种覆盖措施[11]。地膜覆盖具有良好的保水作用,但长期地膜覆盖会加快土壤养分消耗,改变土壤物理性状,降低土壤生物活性,影响农田土壤的生产功能[12]。秸秆覆盖一方面减缓地表水分蒸发,利于雨水下渗,充分利用自然降水[13],另一方面秸秆还田后,经土壤微生物降解,丰富的氮磷钾养分可释放进入土壤,为作物吸收利用[14],秸秆中的碳可增加土壤有机碳供应,改善土壤结构,提升地力[15]。
小麦和马铃薯是甘肃省定西市的主要作物,定西还是全国马铃薯种植的最佳地区之一,也是甘肃省最大的马铃薯产区[16]。小麦与马铃薯的农学特性、根系在土壤中的分布特征以及对土壤养分的吸收特性存在很大差异[17],马铃薯−小麦轮作可以实现对土壤养分协调均衡的利用,提高土壤生产力。因此,我们研究了不同覆盖方式下马铃薯−小麦轮作体系的土壤养分表观平衡,为推荐适合陇中旱地的覆盖模式,减少化肥投入,实现该地区农业的可持续发展提供思路和依据。
1. 材料与方法
1.1 试验区概况
田间试验设在甘肃省定西市安定区唐家堡村甘肃省农业科学院定西试验站(104°36′E,35°35′N),该地区海拔1970 m,年均气温6.2℃,年辐射总量5898 MJ/m2,年日照时数2500 h,≥10℃积温2075.1℃,无霜期140 天,属于中温带半干旱气候。该区为典型旱地雨养农业区,多年平均降水量为415 mm,6—9月降水量占年降水量的68%,降水相对变率24%,400 mm降水保证率为48%。试验区土壤为黄绵土,试验地0—20 cm土层土壤基本化学性质为:有机质10.88 g/kg,全氮0.83 g/kg,速效氮5.6 mg/kg,速效磷7.9 mg/kg,速效钾128 mg/kg,pH为7.75。种植制度为小麦−马铃薯轮作,一年一熟。2022年、2023年的降水及气温如图1所示。
1.2 试验设计
本试验采用单因素随机区组设计,设置4个处理,分别为无覆盖对照(CK)、地膜覆盖(PM)、秸秆碎秆覆盖还田(SR)、秸秆带状覆盖还田(SM),每个处理3次重复,共12个小区,每小区长7 m、宽5 m,小区面积35 m2。试验开始于2022年春。供试马铃薯品种为‘青薯9号’,施肥量为纯N 180 kg/hm2、P2O5 150 kg/hm2;2023年播种小麦,供试品种为‘陇春35号’,施肥量为N 200 kg/hm2、P2O5 200 kg/hm2;肥料种类均为尿素和磷酸二氢铵,均作为基肥在旋耕整地时一次性施入,生育时期内不再追肥。小麦采用穴播,穴距10 cm,行距20 cm,在小麦开花期进行1~2次“一喷三防”作业;马铃薯起垄种植,垄作措施中垄宽60 cm,垄沟宽40 cm,垄高15 cm,垄上等行距呈“品”字形播种,行距40 cm、株距30 cm,划分取样带和测产带。其他管理措施如同当地生产。覆盖措施见表1。
表 1 试验各处理具体实施方案Table 1. Practice of each treatment in the experiment处理
Treatment操作方式 Operation CK 无覆盖 No mulching on the field PM 黑色地膜覆盖,宽120 cm,厚0.01 mm Mulching whole field with black plastic film (120 cm wide, 0.01 mm thick) SR 玉米秸秆铡成5 cm左右的碎秆,覆盖还田量为9000 kg/hm2,上一季所覆盖的秸秆在第二季春季整地时旋耕还田,旋耕深度为15 cm,播种后重新覆盖
The corn straw was chopped into pieces about 5 cm in length, with a mulching return rate of 9000 kg/hm². The straw that was covered in the previous season was incorporated back into the soil during spring soil preparation for the second season using rotary tillage to a depth of 15 cm. After sowing, the field was recovered with straw mulchingSM 田块分种植带和覆盖带,两带相间排列,每年轮换种植带和覆盖带的位置,种植带与覆盖带宽度均为50 cm,总带宽100 cm。覆盖还田量为9000 kg/hm2,春季整地时,将上年覆盖在农田表面的玉米秸秆整秆打碎还田,然后将新的玉米秸秆整秆覆盖在上年种植带的位置,上年覆盖带的位置为当年种植带的位置,此外,马铃薯垄沟为覆盖带
The field is divided into planting strips and mulching strips, arranged alternately and swapped annually. Each strip is 50 cm wide, making the total band width 100 cm. The mulching return rate is 9000 kg/hm². During spring soil preparation, the intact corn straw that was mulched on the field surface in the previous year is chopped and incorporated back into the soil, while new intact corn straw is mulched over the previous planting strips. The previous mulching strips become the planting strips for the current year. Additionally, the potato ridges serve as mulching strips1.3 样品采集与测定
1.3.1 土壤样品采集
分别于2022年马铃薯成熟期和2023年小麦成熟期,在各小区选取3个采样点,用土钻取0—20、20—40、40—60 cm 3个土层的土壤样品,同土层的土壤混合成1份样品,除去石头、地膜等杂质,风干后过2 mm筛备用。SM处理种植带和覆盖带各取3个采样点,养分含量按照种植带和覆盖带占地面积进行加权平均。
1.3.2 植株样品采集
马铃薯收获时在每个小区随机选取10株马铃薯全株,分茎秆和块茎两部分。小麦收获时在每个小区随机选取20株,分为茎秆和籽粒样品。马铃薯茎秆和块茎、小麦茎秆和籽粒在105℃杀青30 min,80℃烘干至恒重,用粉碎机粉碎过筛,用于测定氮、磷、钾含量。
1.3.3 测定项目及计算公式
土壤碱解氮采用碱解扩散法测定;速效磷采用NaHCO3浸提—钼锑抗比色法测定;速效钾用NH4Ac浸提,火焰光度法测定;铵态氮、硝态氮采用KCl浸提,连续流动分析仪测定[18]。
植株样品采用H2SO4−H2O2联合消煮后,分别用凯氏定氮法、分光光度比色法、火焰光度法测定氮、磷、钾含量,粗蛋白含量采用凯氏定氮法测定。
养分平衡采用表观平衡法[19]计算。养分投入量为化肥施入量和由茎秆带入的养分量之和,不考虑降水、大气沉降等带入的养分。养分支出为作物收获而带出的养分量,不考虑因淋洗、挥发和反硝化造成的养分损失。
土壤养分表观盈亏量 = 养分投入量−作物带出养分量
养分表观平衡系数 = 养分投入量/作物带出养分量
养分实际平衡率 = (养分投入量−作物带出养分量)/作物带出养分量×100%。
粗蛋白含量(g/kg) =氮含量×6.25
粗蛋白产量[20](kg/hm2) = 粗蛋白含量×产量/1000
籽粒(块茎)养分积累量[21](kg/hm2) = 籽粒(块茎)干重(kg/hm2)×籽粒(块茎)养分含量(g/kg)/1000
茎秆养分积累量(kg/hm2) = 茎秆生物量(kg/hm2)×茎秆养分含量(g/kg)/1000
1.4 数据处理与统计方法
用Microsoft Excel 2016整理数据,采用SPSS 27.0软件进行统计分析,采用单因素方差分析(ANOVA)及新复极差法(Duncan法)进行多重比较(P<0.05),使用Origin 2021软件绘图。
2. 结果与分析
2.1 不同覆盖方式对作物养分含量的影响
在马铃薯季,不同覆盖方式对马铃薯茎秆和块茎中氮含量影响显著(表2)。马铃薯茎秆氮含量介于16.27~18.57 g/kg,不同处理间差异显著。其中,CK处理氮含量最高,其后依次是SR、SM、PM处理;块茎氮含量介于13.27 ~14.37 g/kg,PM处理块茎氮含量最高,SR和SM处理块茎氮含量显著低于CK处理。马铃薯茎秆钾含量SR处理显著高于其他处理,比CK处理高23.70% (P<0.05)。
表 2 不同覆盖方式对作物养分含量的影响(g/kg)Table 2. Effects of mulching methods on nutrient contents of crops作物
Crop处理
Treatment茎秆 Stalk 籽粒或块茎 Grain or tuber N P K N P K 马铃薯
PotatoCK 18.57±0.30 a 3.45±0.25 a 6.30±0.16 b 13.97±0.12 b 4.02±0.12 a 28.89±0.84 a PM 16.27±0.12 d 3.89±0.28 a 5.89±0.28 b 14.37±0.38 a 4.55±0.35 a 25.04±0.45 a SR 17.37±0.15 b 4.07±0.16 a 7.79±0.76 a 13.47±0.06 c 3.84±0.14 a 28.06±2.60 a SM 16.93±0.23 c 3.95±0.16 a 6.39±0.15 b 13.27±0.06 c 4.06±0.14 a 26.85±0.97 a 小麦
WheatCK 7.28±0.14 b 3.64±0.22 a 15.88±0.89 ab 24.90±0.12 a 3.54±0.98 b 6.51±0.22 a PM 7.72±0.16 a 3.74±0.11 a 18.49±0.67 a 24.67±0.82 a 4.77±1.03 ab 5.55±0.19 b SR 6.70±0.10 c 3.41±0.07 a 18.08±1.34 a 26.07±0.24 a 6.09±0.22 a 5.60±0.06 b SM 5.75±0.11 d 3.41±0.11 a 13.15±0.82 b 26.23±0.41 a 6.35±0.29 a 5.58±0.09 b 注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。同列数据后不同小写字母表示同一作物处理间差异显著 (P<0.05)。
Note: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning. Different lowercase letters after data in a column indicate significant difference among treatments of the same crop (P<0.05).在小麦季,SR和SM处理小麦籽粒磷含量较CK分别显著提高了72.40%和79.64%,而籽粒钾含量在CK处理中最高(P<0.05)。各处理间小麦茎秆氮含量存在显著差异,其中,PM处理最高,其次是CK和SR处理,SM处理最低。
在马铃薯−小麦轮作体系中,两种作物氮和钾含量存在显著差异(P<0.05)。具体而言,马铃薯茎秆的氮含量较高,而块茎的钾含量较高;相反,小麦茎秆的钾含量较高,籽粒的氮含量较高。
2.2 不同覆盖方式对作物养分积累和分配以及粗蛋白产量的影响
由图2可知,与CK处理相比,3种覆盖方式均显著提高了轮作系统两年总养分的积累量。PM、SR、SM处理分别提高轮作系统的氮积累量40.09%、28.27%、18.38%,磷积累量66.29%、45.04%、38.90%,钾积累量55.13%、43.53%、14.53% (P<0.05)。
图 2 不同覆盖方式下作物养分积累及经济部位粗蛋白产量注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。柱上不同小写字母表示处理间差异显著 (P<0.05)。Figure 2. Nutrient accumulation and crude protein yield of economic parts of crops under different mulching methodsNote: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning. Different lowercase letters above the bars indicate significant difference among treatments (P<0.05).在马铃薯季,与CK处理相比,PM、SR、SM处理块茎氮积累量分别提高86.80%、40.62%、23.97%,茎秆氮积累量分别提高12.72%、27.90%、22.80%;块茎磷积累量PM处理显著提高98.60%,SR和SM处理分别提高36.74%、28.28% (P<0.05)。茎秆磷积累量在各覆盖处理之间无显著差异,较CK平均提高53.26%;PM、SR、SM处理块茎钾积累量分别显著提高57.41%、56.72%和21.29%,茎秆钾积累量分别显著提高20.32%、69.14%、36.65%。在小麦季,相较于CK处理,籽粒氮积累量PM、SR、SM处理分别显著提高28.96%、25.84%和19.29%,籽粒磷积累量PM、SR、SM处理间无显著差异,较CK处理平均提高62.43% (P<0.05);小麦茎秆N、P、钾积累量PM显著高于其他处理。
在马铃薯季,PM处理促进了N、P、K向块茎的分配;而在小麦季,SR和SM处理促进了N、P向籽粒的分配。小麦粗蛋白产量显著低于马铃薯粗蛋白产量,小麦粗蛋白产量的贡献主要来自籽粒。
2.3 不同覆盖方式对土壤速效养分含量的影响
在马铃薯季,秸秆覆盖还田后显著提高0—40 cm土层土壤速效磷和速效钾含量,SR显著提高0—20 cm土层土壤碱解氮含量(图3)。与CK处理相比,在0—20 cm土层,SR处理土壤碱解氮含量显著提高39.31%,SR和SM处理土壤速效磷含量分别显著提高14.99%和10.84%,SR和SM处理土壤速效钾含量分别显著提高25.92%和37.96%;在20—40 cm土层,与CK相比,PM处理土壤碱解氮含量显著降低32.34%,SR和SM处理土壤速效磷含量分别显著提高31.97%、41.53%,土壤速效钾含量分别显著提高15.72%和32.45%。在40—60 cm土层,与CK相比,SM处理土壤速效钾含量提高了16.73% (P<0.05)。在小麦季,与CK相比,在0—20 cm土层,SR处理土壤碱解氮含量显著提高21.36%,SR和SM处理土壤速效钾含量分别显著提高21.16%和11.63%;在20—40 cm土层,与CK相比,SR处理土壤速效磷含量和速效钾含量分别显著提高12.03%和14.29%;在40—60 cm土层,与CK相比,SR处理土壤速效磷含量和速效钾含量分别显著提高39.46%、30.67% (P<0.05)。
图 3 不同覆盖方式下0—60 cm土层土壤养分含量注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。柱上不同小写字母表示处理间差异显著(P<0.05)。Figure 3. Soil nutrient contents in 0−60 cm soil layer under different mulching methodsNote: CK—No mulching; PM—Plastic film full mulching; SR—Crushed straw mulching and returning; SM—Straw strip mulching and returning. Different lowercase letters above the bar indicate significant difference among treatments (P<0.05).2.4 不同覆盖方式下的土壤养分表观平衡
2.4.1 土壤氮素表观平衡
在马铃薯−小麦轮作系统中,各处理土壤氮均表现出不同程度的盈余,而且SR、SM处理盈余量显著高于CK和PM处理(P<0.05,表3),与CK相比,SR和SM 处理氮盈余量分别显着增加89.97%和 99.19%,PM处理显着降低37.38%。在马铃薯季,不同处理间的养分表观盈亏量差异显著。由于PM、SR、SM处理均提高了马铃薯氮积累量,因此氮带出量较CK处理分别显著增加41.44%、32.83%和23.25%。PM处理无秸秆氮投入且氮素带出量最高,因此,氮盈余量显著低于CK处理,为36.77 kg/hm2,实际平衡率为24.4%。SR和SM处理盈余量显著高于CK处理,分别为168.33和178.54 kg/hm2,实际平衡率分别为119.0%和136.0%;相比于马铃薯季,小麦季土壤氮盈余量更大,无秸秆还田时盈余量平均为106.61 kg/hm2 (两种无秸秆还田处理的平均值),秸秆还田后盈余量平均为222.49 kg/hm2 (SR和SM平均值)。SR和SM处理盈余量显著高于CK处理,实际平衡率达218.1%~243.5%,表观平衡系数可达3.18~3.43,PM处理氮带出量较CK显著提高38.37%,因此氮盈余量显著低于CK处理,实际平衡率和表观平衡系数分别为78.8%和1.79,表明氮投入过量。在两年轮作系统中,SR和SM处理实际平衡率分别为159.5%、180.6%,CK和PM处理实际平衡率分别为107.3%、48.0%。综上,在实际生产中应适当减少氮投入,特别是小麦季,在秸秆还田后氮素投入可进一步减少。同时,在轮作系统中氮素投入向马铃薯季倾斜。
表 3 不同覆盖方式下的土壤氮素表观平衡Table 3. Soil nitrogen apparent balance under different mulching methods项目
Item处理
Treatment投入量 Input (kg/hm2) 带出量
Output
(kg/hm2)表观盈亏
Apparent balance
(kg/hm2)表观平衡系数
Apparent balance
coefficient实际平衡率 (%)
Actual
balance rate化肥
Fertilizer秸秆
Straw种子
Seed马铃薯
PotatoCK 180.00 0.00 7.38 106.49 d 80.94±0.77 c 1.76 c 76.0 c PM 180.00 0.00 7.38 150.61 a 36.77±1.90 d 1.24 d 24.4 d SR 180.00 122.40 7.38 141.45 b 168.33±0.67 b 2.19 b 119.0 b SM 180.00 122.40 7.38 131.24 c 178.54±0.46 a 2.36 a 136.0 a 小麦
WheatCK 200.00 0.00 5.73 83.17 c 122.56±1.00 b 2.47 b 147.4 b PM 200.00 0.00 5.73 115.08 a 90.65±1.00 c 1.79 c 78.8 c SR 200.00 114.30 5.73 101.82 ab 218.21±8.02 a 3.18 a 218.1 a SM 200.00 114.30 5.73 93.27 bc 226.76±2.09 a 3.43 a 243.5 a 轮作体系
Rotation
systemCK 380.00 0.00 13.11 189.65 d 203.47±1.27 c 2.07 c 107.3 c PM 380.00 0.00 13.11 265.70 a 127.41±2.67 d 1.48 d 48.0 d SR 380.00 236.70 13.11 243.27 b 386.54±8.56 b 2.60 b 159.5 b SM 380.00 236.70 13.11 224.51 c 405.30±2.40 a 2.81 a 180.6 a 注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。同列数据后不同小写字母表示同一项目处理间差异显著 (P<0.05)。
Note: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning. Different lowercase letters after the data in a column indicate significant difference among treatments in the same item (P<0.05).2.4.2 土壤磷素表观平衡
从马铃薯−小麦轮作系统来看,各处理表观平衡系数均超过2.00,除PM处理外,实际平衡率在200.0%以上,说明在轮作系统中磷投入严重过量,与CK相比,SR和SM处理磷盈余量分别显着增加43.75%和46.27%,PM处理显着降低27.30% (表4)。在马铃薯季,PM、SR、SM处理较CK处理磷带出量分别显著增加71.99%、48.80%和40.94% (P<0.05)。PM处理磷盈余量显著低于CK处理,盈余量为25.50 kg/hm2,表观平衡系数为1.61,实际平衡率为61.0%。SR和SM处理由于秸秆磷的投入使得盈余量显著增加,分别为65.03和66.96 kg/hm2,表观平衡系数和实际平衡率分别大于2.50和150.0%;在小麦季,PM、SR、SM处理间磷带出量无显著差异,比CK处理分别高59.70%、40.68%、36.54% (P<0.05)。PM处理盈余量显著低于CK处理,表观平衡系数和实际平衡率分别为2.67和166.6%。SR、SM处理盈余量较CK处理显著增加,表观平衡系数分别高达4.20、4.31,实际平衡率分别高达319.7%、331.4%。每一个试验年度的养分表观盈亏、表观平衡系数和实际平衡率与两年总养分表观盈亏、表观平衡系数和实际平衡率变化趋势一致。
表 4 不同覆盖方式下的土壤磷素表观平衡Table 4. Soil phosphorus apparent balance under different mulching methods项目
Item处理
Treatment投入量 Input (kg/hm2) 带出量
Output
(kg/hm2)表观盈亏
Apparent balance
(kg/hm2)表观平衡系数
Apparent balance
coefficient实际平衡率 (%)
Actual
balance rate化肥
Fertilizer秸秆
Straw种子
Seed马铃薯
PotatoCK 65.50 0.00 2.21 24.54 c 43.17±1.77 b 2.77 a 176.9 a PM 65.50 0.00 2.21 42.21 a 25.50±3.07 c 1.61 b 61.0 b SR 65.50 33.84 2.21 36.52 b 65.03±1.45 a 2.78 a 178.4 a SM 65.50 33.84 2.21 34.59 b 66.96±1.12 a 2.94 a 193.8 a 小麦
WheatCK 89.38 0.00 1.23 21.29 b 68.09±1.78 b 4.25 a 325.3 a PM 89.38 0.00 1.23 34.00 a 55.38±2.79 c 2.67 b 166.6 b SR 89.38 35.46 1.23 29.95 a 94.89±1.80 a 4.20 a 319.7 a SM 89.38 35.46 1.23 29.07 a 95.77±1.37 a 4.31 a 331.4 a 轮作体系
Rotation
systemCK 154.88 0.00 3.44 45.83 c 111.25±4.18 b 3.45 a 244.6 a PM 154.88 0.00 3.44 76.21 a 80.88±2.60 c 2.06 b 106.3 b SR 154.88 69.30 3.44 66.47 b 159.92±3.64 a 3.41 a 241.3 a SM 154.88 69.30 3.44 63.66 b 162.73±1.25 a 3.56 a 255.7 a 注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。同列数据后不同小写字母表示同一项目处理间差异显著 (P<0.05)。
Note: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning. Different lowercase letters after the data in a column indicate significant difference among treatments in the same item (P<0.05).2.4.3 土壤钾素表观平衡
在马铃薯−小麦轮作系统中,与CK相比,SR处理钾亏缺量减少88.18%,SM处理有所盈余,盈余量增加120.12%,PM处理钾亏缺量增加60.73% (表5)。在马铃薯季,各处理钾素均表现为亏缺,秸秆还田后亏缺量显著降低。钾素带出量PM、SR、SM处理较CK分别显著提高49.78%、51.33%和24.45% (P<0.05)。马铃薯钾的亏缺量以PM处理最大,为−146.72 kg/hm2,其次是CK,为−93.20 kg/hm2,二者实际平衡率分别为−91.1%、−86.7%,表观平衡系数均远远小于0.50,说明土壤钾耗竭严重;SR和SM处理钾亏缺量显著降低,分别为−40.30和−11.40 kg/hm2,二者表观平衡系数均小于1,钾仍处于亏缺状态,说明仅秸秆钾的输入无法满足马铃薯对钾的需求;在小麦季,钾素带出量仅PM处理较CK显著提高64.59%,钾的表观盈亏趋势与马铃薯一致,SM>SR>CK>PM,但在秸秆覆盖还田处理下钾表现出一定量的盈余,SR和SM处理分别盈余22.30和42.24 kg/hm2,表观平衡系数分别为1.31和1.72,实际平衡率分别为28.2%和71.5%,说明秸秆覆盖还田可以满足小麦对钾的需求。在马铃薯小麦轮作系统中,CK和PM处理钾亏缺严重,秸秆覆盖还田后钾基本达到平衡。并且在马铃薯−小麦轮作系统中,小麦季的低钾需求,有利于次季马铃薯对钾的吸收利用。
表 5 不同覆盖方式下的土壤钾素表观平衡Table 5. Soil potassium apparent balance under different mulching methods项目
Item处理
Treatment投入量 Input (kg/hm2) 带出量
Output
(kg/hm2)表观盈亏
Apparent balance
(kg/hm2)表观平衡系数
Apparent balance
coefficient实际平衡率 (%)
Actual
balance rate化肥
Fertilizer秸秆
Straw种子
Seed马铃薯
PotatoCK 0.00 0.00 14.30 107.50 c −93.20±1.35 c 0.13 c −86.7 c PM 0.00 0.00 14.30 161.02 a −146.72±4.62 d 0.09 d −91.1 d SR 0.00 108.09 14.30 162.67 a −40.30±4.32 b 0.75 b −24.7 b SM 0.00 108.09 14.30 133.79 b −11.40±0.93 a 0.91 a −8.5 a 小麦
WheatCK 0.00 0.00 1.23 60.91 b −59.61±3.86 c 0.02 c −97.9 c PM 0.00 0.00 1.23 100.25 a −98.95±6.49 d 0.01 c −98.7 c SR 0.00 100.04 1.23 79.04 b 22.30±8.81 b 1.31 b 28.2 b SM 0.00 100.04 1.23 59.10 b 42.24±2.56 a 1.72 a 71.5 a 轮作体系
Rotation
systemCK 0.00 0.00 15.53 168.42 d −152.89±4.80 c 0.09 c −90.8 c PM 0.00 0.00 15.53 261.27 a −245.74±3.17 d 0.06 c −94.1 c SR 0.00 208.13 15.53 241.73 b −18.07±10.08 b 0.93 b −7.2 b SM 0.00 208.13 15.53 192.89 c 30.77±2.03 a 1.16 a 16.0 a 注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。同列数据后不同小写字母表示同一项目处理间差异显著 (P<0.05)。
Note: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning. Different lowercase letters after the data in a column indicate significant difference among treatments in the same item (P<0.05).2.5 土壤养分表观平衡与0—20 cm土层土壤养分含量间的相关关系
对所有采样点0—20 cm土层碱解氮、速效磷和速效钾与对应的氮磷钾表观平衡值的相关性分析表明,二者均呈极显著正相关关系。这说明土壤速效养分随养分表观平衡值的增加呈现上升趋势(图4)。
图 4 土壤养分表观平衡与土壤养分含量的相关关系注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。Figure 4. Correlation between soil nutrient apparent balance and soil nutrient contentNote: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning.3. 讨论
3.1 马铃薯−小麦轮作体系不同覆盖措施下的养分积累量
土壤养分是影响作物产量形成的重要因素,土壤养分含量的高低影响养分在作物各个器官的分配,秸秆还田是土壤养分的重要来源之一,秸秆还田后经过微生物的腐解释放养分,对提升土壤肥力、改良耕地质量有关键意义[22]。刘丽华等[23]通过盆栽试验,研究了秸秆还田对水稻植株吸收、转运和分配氮、磷、钾的影响,结果表明,秸秆还田可以促进水稻植株氮、磷、钾的积累;唐海明等[24]研究冬季不同秸秆覆盖对后茬水稻氮、磷、钾转运与分配的影响,发现秸秆还田促进了水稻各部位干物质的积累和转运。本研究中,SR和SM处理促进植株N、P、K积累(图2),并且可以有效提高土壤肥力(图3),与前人研究结果基本一致。秸秆还田后向土壤中投入了丰富的碳源,促进了微生物的繁殖,进而促进秸秆腐解释放养分,供作物吸收利用[25]。而且秸秆覆盖减少了地表水分蒸发,有利于雨水的下渗,促进作物有效利用自然降水[13]。小麦籽粒与秸秆养分积累量直观反映出干物质的生产与分配,而小麦对养分的吸收利用及转运与小麦产量密切相关[26]。本研究结果表明,与CK相比,PM处理显著提高了小麦茎秆和籽粒的氮、磷、钾积累量,SR和SM处理仅显著提高了小麦籽粒养分积累量,说明秸秆还田后,促进了氮磷钾向小麦籽粒的分配。
3.2 马铃薯−小麦轮作体系不同覆盖措施下的土壤养分含量
据文献[27]报道,每生产1000 kg马铃薯吸氮量约为3.0 ~4.0 kg,每生产1000 kg小麦吸氮量约为2.87 kg;土壤速效磷是土壤磷库中对作物最有效的部分,是评价土壤供磷能力的重要指标[28]。王平等[29]对不同覆盖方式下土壤养分的研究结果表明,不同覆盖方式影响马铃薯根际土壤有机质和养分含量,地膜覆盖对土壤养分的作用比秸秆覆盖小。本研究结果表明,SR和SM处理对于土壤速效养分均有提高,而PM处理的影响作用并不显著(图3),这也与卜玉山等[12]的研究结果一致。此外,与CK处理相比,秸秆还田后40—60 cm土层中土壤养分显著提高,这可能是因为在15—20 cm土层中秸秆经微生物活动和生化反应分解后,随水分入渗并在深层土壤中积累[30];SR和SM提高了土壤速效磷含量(图3),这与前人研究结果一致,土壤中的磷固存依赖于其与土壤颗粒结合,而秸秆还田使土壤胶体表面的磷吸附位点部分被占据,减弱了磷的吸附性能,从而使得土壤中速效磷含量显著增加 [31];氮、磷是黄土高原区土壤养分的主要限制因子,而土壤钾库容量较大,能够满足作物对钾素的需要[32];前人研究表明,秸秆还田后,除了秸秆腐解释放大量的钾以外,还可以增加土壤有机质,而土壤有机质的增加可以为K+提供更多高亲和力强的位点[33]。在本研究中,秸秆还田显著提高了土壤中速效钾含量,与前人研究结果基本一致。两个试验年份均未施钾肥,马铃薯收获后只有CK和PM处理下速效钾接近黄土高原大田作物0—20 cm土层钾素临界值110 mg/kg[34],秸秆覆盖还田都远远高于这个值,而在小麦收获后,除SM处理外,土壤速效钾较马铃薯收获后都有不同程度提高,CK和PM处理分别提高了21.04%、19.82%,SR处理提高了14.46%,并且在20—40 cm土层中提高趋势一致。表明,马铃薯−小麦轮作可以有效缓解连作对地力的持续性消耗。
3.3 马铃薯−小麦轮作体系不同覆盖措施下的土壤养分表观平衡
农田氮、磷、钾的盈余量反映了土壤养分的变化方向,不同农田生态系统由于气候、地形、农田管理措施的差异,会影响土壤养分的吸收、转移和固存,从而影响土壤养分平衡[35]。胡乃月[36]研究发现,秸秆还田后N、P盈余量增加,为此提出在秸秆还田条件下可以适量减少氮磷肥的施用量。本研究中,从马铃薯−小麦轮作体系来看,氮磷表现出大量盈余,而且秸秆还田增加了秸秆氮磷的输入,盈余量显著增加,这与聂云等[37]的研究结果一致。钾素从收支平衡来看,表现为亏缺,马铃薯季亏缺更加严重,一方面可能与马铃薯的吸钾性有关,另一方面马铃薯钾素积累是小麦的1.89倍,钾素带出量更大。而秸秆还田可以有效缓解钾素亏缺。刘瑞等[38]在小麦−玉米轮作体系下研究了土壤养分和土壤养分平衡值之间的关系,结果表明,土壤养分含量与相应的土壤养分平衡值呈极显著正相关关系。本研究结果表明,马铃薯−小麦轮作系统下0—20 cm土层土壤碱解氮、速效磷和速效钾,与土壤氮、磷、钾表观平衡值均呈极显著正相关关系,这与孙波等[35]的研究结果一致。
4. 结论
在陇中旱地农田现有施肥量和措施下,3种覆盖措施均能提高马铃薯和小麦氮、磷、钾积累量,地膜覆盖提高幅度最大,秸秆碎秆覆盖还田次之,秸秆整秆覆盖还田最低。地膜覆盖对土壤养分的作用不显著,两种秸秆覆盖还田措施均不同程度提高了土壤速效养分,秸秆碎秆覆盖还田提高效果更佳。马铃薯−小麦轮作系统中氮磷盈余,钾亏缺。地膜覆盖降低了氮磷盈余,加剧了钾素亏缺,两种秸秆覆盖还田加剧了氮磷盈余,有效缓解了钾素亏缺,特别是在不施钾肥情况下,其较地膜覆盖缓解钾素亏缺量达97.56 kg/hm2。实际生产中秸秆还田时适当减少氮磷肥投入,无秸秆还田时要增施钾肥,马铃薯−小麦轮作中肥料分配时氮磷钾肥适当向马铃薯季倾斜。
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图 2 不同覆盖方式下作物养分积累及经济部位粗蛋白产量
注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。柱上不同小写字母表示处理间差异显著 (P<0.05)。
Figure 2. Nutrient accumulation and crude protein yield of economic parts of crops under different mulching methods
Note: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning. Different lowercase letters above the bars indicate significant difference among treatments (P<0.05).
图 3 不同覆盖方式下0—60 cm土层土壤养分含量
注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。柱上不同小写字母表示处理间差异显著(P<0.05)。
Figure 3. Soil nutrient contents in 0−60 cm soil layer under different mulching methods
Note: CK—No mulching; PM—Plastic film full mulching; SR—Crushed straw mulching and returning; SM—Straw strip mulching and returning. Different lowercase letters above the bar indicate significant difference among treatments (P<0.05).
图 4 土壤养分表观平衡与土壤养分含量的相关关系
注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。
Figure 4. Correlation between soil nutrient apparent balance and soil nutrient content
Note: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning.
表 1 试验各处理具体实施方案
Table 1 Practice of each treatment in the experiment
处理
Treatment操作方式 Operation CK 无覆盖 No mulching on the field PM 黑色地膜覆盖,宽120 cm,厚0.01 mm Mulching whole field with black plastic film (120 cm wide, 0.01 mm thick) SR 玉米秸秆铡成5 cm左右的碎秆,覆盖还田量为9000 kg/hm2,上一季所覆盖的秸秆在第二季春季整地时旋耕还田,旋耕深度为15 cm,播种后重新覆盖
The corn straw was chopped into pieces about 5 cm in length, with a mulching return rate of 9000 kg/hm². The straw that was covered in the previous season was incorporated back into the soil during spring soil preparation for the second season using rotary tillage to a depth of 15 cm. After sowing, the field was recovered with straw mulchingSM 田块分种植带和覆盖带,两带相间排列,每年轮换种植带和覆盖带的位置,种植带与覆盖带宽度均为50 cm,总带宽100 cm。覆盖还田量为9000 kg/hm2,春季整地时,将上年覆盖在农田表面的玉米秸秆整秆打碎还田,然后将新的玉米秸秆整秆覆盖在上年种植带的位置,上年覆盖带的位置为当年种植带的位置,此外,马铃薯垄沟为覆盖带
The field is divided into planting strips and mulching strips, arranged alternately and swapped annually. Each strip is 50 cm wide, making the total band width 100 cm. The mulching return rate is 9000 kg/hm². During spring soil preparation, the intact corn straw that was mulched on the field surface in the previous year is chopped and incorporated back into the soil, while new intact corn straw is mulched over the previous planting strips. The previous mulching strips become the planting strips for the current year. Additionally, the potato ridges serve as mulching strips表 2 不同覆盖方式对作物养分含量的影响(g/kg)
Table 2 Effects of mulching methods on nutrient contents of crops
作物
Crop处理
Treatment茎秆 Stalk 籽粒或块茎 Grain or tuber N P K N P K 马铃薯
PotatoCK 18.57±0.30 a 3.45±0.25 a 6.30±0.16 b 13.97±0.12 b 4.02±0.12 a 28.89±0.84 a PM 16.27±0.12 d 3.89±0.28 a 5.89±0.28 b 14.37±0.38 a 4.55±0.35 a 25.04±0.45 a SR 17.37±0.15 b 4.07±0.16 a 7.79±0.76 a 13.47±0.06 c 3.84±0.14 a 28.06±2.60 a SM 16.93±0.23 c 3.95±0.16 a 6.39±0.15 b 13.27±0.06 c 4.06±0.14 a 26.85±0.97 a 小麦
WheatCK 7.28±0.14 b 3.64±0.22 a 15.88±0.89 ab 24.90±0.12 a 3.54±0.98 b 6.51±0.22 a PM 7.72±0.16 a 3.74±0.11 a 18.49±0.67 a 24.67±0.82 a 4.77±1.03 ab 5.55±0.19 b SR 6.70±0.10 c 3.41±0.07 a 18.08±1.34 a 26.07±0.24 a 6.09±0.22 a 5.60±0.06 b SM 5.75±0.11 d 3.41±0.11 a 13.15±0.82 b 26.23±0.41 a 6.35±0.29 a 5.58±0.09 b 注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。同列数据后不同小写字母表示同一作物处理间差异显著 (P<0.05)。
Note: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning. Different lowercase letters after data in a column indicate significant difference among treatments of the same crop (P<0.05).表 3 不同覆盖方式下的土壤氮素表观平衡
Table 3 Soil nitrogen apparent balance under different mulching methods
项目
Item处理
Treatment投入量 Input (kg/hm2) 带出量
Output
(kg/hm2)表观盈亏
Apparent balance
(kg/hm2)表观平衡系数
Apparent balance
coefficient实际平衡率 (%)
Actual
balance rate化肥
Fertilizer秸秆
Straw种子
Seed马铃薯
PotatoCK 180.00 0.00 7.38 106.49 d 80.94±0.77 c 1.76 c 76.0 c PM 180.00 0.00 7.38 150.61 a 36.77±1.90 d 1.24 d 24.4 d SR 180.00 122.40 7.38 141.45 b 168.33±0.67 b 2.19 b 119.0 b SM 180.00 122.40 7.38 131.24 c 178.54±0.46 a 2.36 a 136.0 a 小麦
WheatCK 200.00 0.00 5.73 83.17 c 122.56±1.00 b 2.47 b 147.4 b PM 200.00 0.00 5.73 115.08 a 90.65±1.00 c 1.79 c 78.8 c SR 200.00 114.30 5.73 101.82 ab 218.21±8.02 a 3.18 a 218.1 a SM 200.00 114.30 5.73 93.27 bc 226.76±2.09 a 3.43 a 243.5 a 轮作体系
Rotation
systemCK 380.00 0.00 13.11 189.65 d 203.47±1.27 c 2.07 c 107.3 c PM 380.00 0.00 13.11 265.70 a 127.41±2.67 d 1.48 d 48.0 d SR 380.00 236.70 13.11 243.27 b 386.54±8.56 b 2.60 b 159.5 b SM 380.00 236.70 13.11 224.51 c 405.30±2.40 a 2.81 a 180.6 a 注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。同列数据后不同小写字母表示同一项目处理间差异显著 (P<0.05)。
Note: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning. Different lowercase letters after the data in a column indicate significant difference among treatments in the same item (P<0.05).表 4 不同覆盖方式下的土壤磷素表观平衡
Table 4 Soil phosphorus apparent balance under different mulching methods
项目
Item处理
Treatment投入量 Input (kg/hm2) 带出量
Output
(kg/hm2)表观盈亏
Apparent balance
(kg/hm2)表观平衡系数
Apparent balance
coefficient实际平衡率 (%)
Actual
balance rate化肥
Fertilizer秸秆
Straw种子
Seed马铃薯
PotatoCK 65.50 0.00 2.21 24.54 c 43.17±1.77 b 2.77 a 176.9 a PM 65.50 0.00 2.21 42.21 a 25.50±3.07 c 1.61 b 61.0 b SR 65.50 33.84 2.21 36.52 b 65.03±1.45 a 2.78 a 178.4 a SM 65.50 33.84 2.21 34.59 b 66.96±1.12 a 2.94 a 193.8 a 小麦
WheatCK 89.38 0.00 1.23 21.29 b 68.09±1.78 b 4.25 a 325.3 a PM 89.38 0.00 1.23 34.00 a 55.38±2.79 c 2.67 b 166.6 b SR 89.38 35.46 1.23 29.95 a 94.89±1.80 a 4.20 a 319.7 a SM 89.38 35.46 1.23 29.07 a 95.77±1.37 a 4.31 a 331.4 a 轮作体系
Rotation
systemCK 154.88 0.00 3.44 45.83 c 111.25±4.18 b 3.45 a 244.6 a PM 154.88 0.00 3.44 76.21 a 80.88±2.60 c 2.06 b 106.3 b SR 154.88 69.30 3.44 66.47 b 159.92±3.64 a 3.41 a 241.3 a SM 154.88 69.30 3.44 63.66 b 162.73±1.25 a 3.56 a 255.7 a 注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。同列数据后不同小写字母表示同一项目处理间差异显著 (P<0.05)。
Note: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning. Different lowercase letters after the data in a column indicate significant difference among treatments in the same item (P<0.05).表 5 不同覆盖方式下的土壤钾素表观平衡
Table 5 Soil potassium apparent balance under different mulching methods
项目
Item处理
Treatment投入量 Input (kg/hm2) 带出量
Output
(kg/hm2)表观盈亏
Apparent balance
(kg/hm2)表观平衡系数
Apparent balance
coefficient实际平衡率 (%)
Actual
balance rate化肥
Fertilizer秸秆
Straw种子
Seed马铃薯
PotatoCK 0.00 0.00 14.30 107.50 c −93.20±1.35 c 0.13 c −86.7 c PM 0.00 0.00 14.30 161.02 a −146.72±4.62 d 0.09 d −91.1 d SR 0.00 108.09 14.30 162.67 a −40.30±4.32 b 0.75 b −24.7 b SM 0.00 108.09 14.30 133.79 b −11.40±0.93 a 0.91 a −8.5 a 小麦
WheatCK 0.00 0.00 1.23 60.91 b −59.61±3.86 c 0.02 c −97.9 c PM 0.00 0.00 1.23 100.25 a −98.95±6.49 d 0.01 c −98.7 c SR 0.00 100.04 1.23 79.04 b 22.30±8.81 b 1.31 b 28.2 b SM 0.00 100.04 1.23 59.10 b 42.24±2.56 a 1.72 a 71.5 a 轮作体系
Rotation
systemCK 0.00 0.00 15.53 168.42 d −152.89±4.80 c 0.09 c −90.8 c PM 0.00 0.00 15.53 261.27 a −245.74±3.17 d 0.06 c −94.1 c SR 0.00 208.13 15.53 241.73 b −18.07±10.08 b 0.93 b −7.2 b SM 0.00 208.13 15.53 192.89 c 30.77±2.03 a 1.16 a 16.0 a 注:CK—无覆盖对照;PM—地膜覆盖;SR—秸秆碎秆覆盖还田;SM—秸秆带状覆盖还田。同列数据后不同小写字母表示同一项目处理间差异显著 (P<0.05)。
Note: CK—No mulching control; PM—Full mulching with plastic film; SR—Full mulching with crushed straw and returning; SM—Strip mulching with whole straws and returning. Different lowercase letters after the data in a column indicate significant difference among treatments in the same item (P<0.05). -
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