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东非高原半干旱区垄沟覆盖结构变化对小麦生产力和土壤质量的影响及其机理

Effects of Structural Variation on Wheat Productivity and Soil Quality and Its Mechanism under Ridge-furrow Mulching Farming System in Semiarid East African Plateau

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【Author in Chinese】 罗崇亮

【Supervisor】 熊友才

【Author's Information】 兰州大学, 生态学, 2020, 博士

【Abstract in Chinese】 半干旱雨养农业区垄沟覆盖栽培系统对提高作物生产力具有显著的促进作用,但生产力经常受系统结构因子的影响,包括垄沟尺寸、覆盖材料、覆盖方式、种植密度和土壤可利用营养元素等。垄沟覆盖栽培系统生产力与结构变化的耦合关系属于农业生态学领域的热点问题,对该问题的探索及机理揭示涉及该系统适应性管理和大面积推广应用的基础科学问题,尤其在东非高原半干旱雨养农业区尚未见报道。本研究于2015-2017年在位于肯尼亚东部半干旱区-Juja开展了四个生长季的大田试验,包含了4个相对独立,但又紧密相关的试验。具体包括:1)不同覆盖材料和覆盖方式下小麦生产力响应规律,水热调控机理和土壤质量变化;2)垄沟覆膜条件下种植密度对小麦异速关系和产量形成的影响;3)不同垄沟尺寸条件下小麦生产力响应规律及水热调控机理;4)垄沟覆盖条件下氮磷施加对小麦生产力响应规律和土壤质量变化。试验采集了气候因子、小麦生长、水分利用、产量形成、土壤储水、土壤温度、土壤养分等土壤质量和作物生态指标。探究了垄沟覆盖条件下小麦生产力与结构变化之间的量化关系,并分析了水分利用效率及土壤养分变化规律,得出如下主要结论:1.不同垄沟覆盖方式下小麦生产力响应规律及水热调控机理。试验包括六个不同垄沟覆盖栽培方式,分别为1)垄上覆黑膜沟内覆秸秆(RFBG),2)垄上覆透明膜沟内覆秸秆(RFtS),3)垄上覆黑膜沟内无覆盖(RFb),4)垄上覆透明膜沟内无覆盖(RFt),5)垄和沟均覆秸秆(RFS)以及6)垄沟无覆盖对照组(CK)。结果表明,RFbS,RFtS,RFb,RFt和RFS在四个生长季的产量较对照分别增加了79-125.4%,75.1-133.7%,59.3-86.3%,46.3-93.6%和35.4-44.1%;而水分利用效率则分别增加了125.7-163.2%,118.6-170.2%,71.6-105.3%,60.5-110.5%和37-54.4%。相比于对照,RFbS和RFtS的经济效益增幅最大,RFb和RFt次之,RFS增幅最低。与对照相比,RFbS,RFtS,RFt,RFb和RFS在四个生长季中均显著提高了土壤水分。RFbS和RFtS土壤水分增加幅度最大,RFb和RFt次之,RFS增加幅度最小。不同垄沟覆盖处理中土壤温度由高到低依次为RFt,RFtS,RFb,RFbS,RF和RFS。与对照相比,覆膜增加了土壤温度,白膜较黑膜增加幅度大;覆盖秸秆则显著降低了土壤温度。在所有垄沟覆盖栽培方式中,垄沟地膜和秸秆二元覆盖对肯尼亚旱作小麦增产增效潜力最大,改善了土壤水热条件,增加了小麦生产力和经济效益。2.不同垄沟覆盖方式下土壤质量变化。与对照相比,RFbS,RFtS和RFS显著增加了耕层(0-30 cm)土壤有机碳(SOC)和全氮(STN)含量;而RFb和RFt则显著降低了土壤有机碳和全氮含量。与RFb和RFt相比,RFbS和RFtS增加了土壤C:N比。在RFbS和RFtS中硝态氮和铵态氮的含量显著高于其他处理。与对照相比RFbS,RFtS和RFS显著增加了土壤pH,降低了土壤容重。RFtS和RFbS显著提升了土壤养分并改善了土壤质量和结构,提高了土壤有机碳含量,有效减缓耕地土壤退化。3.垄沟覆盖条件下小麦产量和水分利用的密度依赖曲线特征及机理。试验设耕作方式和种植密度两组处理。耕作方式设2个处理:1)垄沟覆膜(RFM)和2)传统平作(CK);种植密度设6个处理,播种量分别是60,140,220,300,380和460 kg ha-1。结果表明,小麦个体的繁殖分配和繁殖效率随密度的增加而降低。而在群体水平上,最大产量出现在中密度,但个体繁殖分配较小。通过主成分分析,在密度为220 kg ha-1时,有着较好的群体表现。在RFM耕作方式下,尽管小麦群体产量在中密度之后开始降低,但是群体生物量在密度为300,380和460时并无显著差异。与对照相比,RFM耕作方式在不同密度下均显著增加了小麦个体的繁殖分配和繁殖分配效率。4.不同垄沟尺寸对小麦生产力及土壤水热变化的影响。试验包括垄沟覆膜栽培方式下7个不同的垄沟宽度比,分别是1)40:20(R4F2),2)30:20(R3F2),3)20:20(R2F2),4)30:40(R3F4),5)20:40(R2F4),6)30:60(R3F6)和7)20:60(R2F6),以传统平作无覆盖作为对照组(CK)。结果表明,土壤水分和温度随垄沟比的增加而逐渐降低。与对照相比,R4F2,R3F2,R2F2,R3F4和R2F4的土壤水分显著较高;而R4F2,R3F2和R2F2的土壤温度显著高于对照。垄沟覆膜显著增加了小麦产量和水分利用效率,R2F2增加幅度最大,产量比对照增加了83.8%-90.3%,而水分利用效率增加了103.7%-115.6%。通过非线性拟合,小麦产量,水分利用效率和收获指数的最大值分别出现在垄沟比为1.3-1.38,1.37-1.45和1.45-1.56之间。通过线性拟合,小麦产量和水分利用效率随垄沟带型宽度的增加而降低。因此,R3F2和R2F2垄沟覆膜栽培方式显著改善了土壤水热状况,是提升小麦生产力的最优垄沟比。5.不同垄高对小麦生产力及土壤水热变化的影响。垄沟覆膜栽培方式下设3个垄高梯度,具体包括1)高垄(HR),2)中垄(MR),3)低垄(LR)和4)传统平作无覆盖对照组(CK)。三种垄高处理中的土壤水分和温度均显著高于对照。随着垄高的增加,土壤水分逐渐增加,而土壤温度则逐渐降低。相比于对照,不同垄高处理均显著增加了小麦产量和水分利用效率,中垄增幅最大,分别增加了82.8%-90.3%和103.7-115.6%。中垄显著改善了土壤水热条件,能够较好地为耕地土壤增温保墒,小麦增产效果明显。6.垄沟覆膜条件下氮磷施加对小麦生产力的影响。采用双因素裂区设计,主因子为耕作方式:垄沟均覆盖地膜(RFM)和传统平作无覆盖处理(FP)。副因子为氮和磷肥施加:对照组无化肥添加(CK)、氮添加(N)、磷添加(P)和氮磷添加(NP)。结果发现,耕作方式和氮磷肥添加及其交互作用均对小麦产量,生物量和水分利用效率有显著影响。在垄沟覆膜(RFM)和传统平作(FP)处理中,N、P和NP添加均显著增加了小麦产量,生物量和水分利用效率。对于产量而言,在RFM处理中N,P和NP添加较对照分别增加了75.5-80.4%,69.3-90.6%和116.4-129.6%;在FP组中,N、P和NP添加较对照分别增加了76.5-135.3%,100-126.3%和119.3-169.5%。对于水分利用效率,在RFM处理中N、P和NP添加较对照分别增加了97.8-101.4%,94.1-114.5%和155.5-181.3%;而在FP组中,N、P和NP添加较对照分别增加了108.1-187%,137.5-179.2%和208.6-261.3%。氮磷显著增加了小麦产量,生物量和水分利用效率。7.垄沟覆盖条件下氮磷施加对土壤质量的影响。结果表明,N添加显著降低了土壤C-CO2释放,而P添加则显著增加了土壤C-CO2释放,NP添加则对土壤C-CO2释放无显著影响。N添加增加了土壤可溶性有机碳和速效氮含量,导致土壤酸化,降低土壤微生物生物量和酶活性,从而降低有机质的分解;而P添加增加了土壤可溶性碳和速效磷含量,提高了分解纤维素、氨基葡萄糖、多胺及木质素的酶活性,降低了酸性磷酸酶活性,并最终加速了土壤有机质的矿化。相比于传统平作(FP),垄沟覆膜(RFM)显著增加了土壤可溶性碳,微生物生物量和酶活性,进而加速了土壤C-CO2释放。综上所述,垄沟覆盖系统结构变化导致旱地小麦农田生产力发生改变,土壤质量和土壤墒情也随之改变,从而影响农田生态系统的服务功能和可持续发展。本研究立足生态系统结构与功能关系理论,揭示了垄沟尺寸、覆盖方式、植物种群密度和氮磷添加等对小麦产量、水分利用和土壤质量的影响规律。总结得出,垄沟地膜和秸秆二元覆盖、小麦种植密度为220 kg ha-1、垄沟比为1-1.5、垄沟单元尺寸为40 cm、垄高为15 cm和合理的氮磷肥配施是东非高原半干旱地区最优的垄沟结构配置,对农田生产力和土壤质量具有双重促进作用,为应对全球气候变化和粮食安全提供了理论依据和科学支撑。

【Abstract】 The ridge-furrow with mulching system(RFM)has a significant effect on improving crop productivity in semi-arid area.But crop productivity has affected by the changing of the RFM system structural factors,including the ridge-furrow size,mulching material,mulching pattern,planting density and soil nutrients.The coupling relationship between productivity and the structure of RFM system is a hot spot in agroecology.It involves the basic scientific issues to adopt land management and large-scale application for farmers in RFM system,which has not yet been reported,especially in semi-arid rainfed region of eastren Africa Plateau(EAP).In this study,field experiment with four growing seasons was conducted in Juja,a typical semiarid site of Kenya from 2015 to 2017.It comprises four relatively independent but closely related field experiments:1)wheat productivity respond mechanisms,soil hydrothermal regulative mechanisms and soil quantity under different mulching materials and mulching patterns;2)allometric relationship and yield formation in response to planting density under ridge-furrow plastic mulching in rainfed wheat;3)wheat productivity responses and hydrothermal regulative mechanisms under different ridge-furrow sizes;4)the effects of nitrogen and phosphorus addition on wheat productivity and soil quality under ridge-furrow with mulching plastic.The objectives of this study are to evaluate the quantitative relationship between wheat productivity,water use efficiency and soil physicochemical properties with RFM system structural changes.The main conclusion is as follows:1.Wheat productivity and soil hydrothermal status under different mulching materials and mulching patterns.The experiment was a randomized block design with three replicates for each treatment.Mulching treatments included as follows:1)furrows mulched with wheat straw and ridges mulched with black plastic film(RFbS),2)furrows mulched with wheat straw and ridges mulched with transparent plastic film(RFtS),3)furrows unmulched and ridges mulched with black plastic film(RFB),4)furrows unmulched and ridges mulched with transparent plastic film(RFW)and 5)furrows and ridges both mulched with wheat straw(RFS).No mulching in RF was used as control group(CK).The results showed that yield under RFbS,RFtS,RFb,RFt and RFS increased by 79-125.4%,75.1-133.7%,59.3-86.3%,46.3-93.6%and35.4-44.1%,compared with CK in the four growing seasons,respectively.Water use efficiency increased by 125.7-163.2%,118.6-170.2%,71.6-105.3%,60.5-110.5%and 37-54.4%,respectively.Compared with CK,RFbS,RFtS,RFb,RFt and RFS significantly increased soil water storage during the four growing seasons.The order of soil temperature was first RFt,next RFtS,then RFb,RFbS,RF and RFS.Compared with CK,plastic mulching increased soil temperature under white plastic mulching more than black plastic mulching,and mulching straw decreased soil temperature.Among all the ridge-furrow with mulching systems,RFbS and RFtS had the greatest potential for increasing wheat yield and water use efficiency,improved soil water and temperature conditions,and eventually increased wheat productivity and economic benefits.2.Effects of soil quality on different mulching materials and mulching patterns.Compared with CK,RFbS,RFtS and RFS increased significantly soil organic carbon(SOC)and total nitrogen(STN)content,but RFb and RFt significantly reduced SOC and STN.Soil C:N ratio under RFbS and RFtS significantly decreased than that under RFb and RFt.NO3--N and NH4+-N contents under RFbS and RFtS significantly increased than those under other treatments.Compared with CK,RFbS,RFtS and RFS significantly increased soil pH and reduced soil bulk density.RFtS and RFbS significantly enhanced soil nutrients,improved soil quality and structure,increased soil organic carbon content,and effectively alleviated soil degradation.3.Density-dependent yield formation and allometric relationships under ridge and furrow with mulching.We conducted a density-dependent yield-formation experiment in field-grown wheat with flat planting(CK)and ridge-furrow with plastic-film mulch(RFM).Planting densities set as 60,140,220,300,380 and 460 kg ha-1 seed rates.We found that increased wheat population density(60,140,220,300,380 and 460 kg ha-1)tended to lower the reproductive allocation and efficiency of conversion of vegetative biomass into reproductive biomass at individual level.Yet at population level,the maximum reproductive output was observed at a medium density(300-380 kg ha-1),while it was not beneficial to individual survival and reproduction.The principal component analyses(PCA)showed that there were good individual and population performance at 220 kg ha-1.While the harvestable yield of wheat declined from the peak of medium density(300-380 kg ha-1),total biomass yield increased with density and then leveled off at 300,380 and 460.Our results showed that RFM system was significantly higher reproduction allocation and efficiency of conversion of vegetation into reproduction compared to conventional flat planting pattern(CK).4.Effects of ridge-furrow ratio on wheat productivity,soil water and temperature under ridge-furrow with mulching plastic.The field experiment was composed of seven different levels of ridge-furrow ratios under ridge-furrow with mulching plastic(RFM)and flat plating with no mulching(CK).The ridge-furrow ratios as follows:1)40:20,(R4F2);2)30:20,(R3F2);3)20:20,(R2F2);4)30:40,(R3F4);5)20:40,(R2F4);6)30:60,(R3F6)and 7)20:60(R2F6).The results showed that soil moisture and temperature decreased with the increases of ridge-furrow ratio.Compared with CK,the soil moisture storage under R4F2,R3F2,R2F2,R3F4 and R2F4 significantly increased,and soil temperature under R4F2,R3F2 and R2F2 were significantly higher than that under CK.RFM significantly increased wheat yield and water use efficiency,the increases under R2F2 was highest.Wheat yield under R2F2 increased by83.8%-90.3%compared to CK,and water use efficiency increased by103.7%-115.6%.Through nonlinear fitting,the maximum values of wheat yield,water use efficiency and harvest index appeared in the ridge-furrow ratio of 1.3-1.38,1.37-1.45 and 1.45-1.56,respectively.Wheat yield and water use efficiency decreased with the increase of ridge-furrow width by linear fitting.In summary,R3F2and R2F2 significantly improved the soil water and temperature conditions,and was the optimum ridge-furrow ratio for improving wheat productivity.5.Effects of ridge height on wheat productivity,soil water and temperature under ridge-furrow with mulching plastic.The field experiment was composed of three different levels of ridge heights(i.e.high ridge(HR),medium ridge(MR)and low ridge(LR))under ridge-furrow with mulching plastic(RFM)and flat plating with no mulching(CK).Soil moisture and temperature under the three ridge height treatments were significantly higher than those under CK.With the increase of ridge height,soil moisture increased,but the soil temperature decreased.Compared with CK,wheat yield and water use efficiency were significantly increased in all ridge height treatments.Wheat yield and water use efficiency were the greatest,and increased by82.8%-90.3%and 103.7-115.6%,respectively.The medium ridge significantly improved the soil water and temperature conditions,which could increase wheat productivity.6.Effects of nitrogen and phosphorus addition on wheat productivity under ridge-furrow with mulching system.This study was designed to explore the effects of farming system and nutrient addition.The farming system included ridge-furrow with mulching plastic(RFM)and flat plating(FP).The nutrient addition was used four treatments as follows:control treatment without fertilizer addition(CK),nitrogen addition(N),phosphorus addition(P),and nitrogen and phosphorus addition(NP).We found that farming system,nutrient addition and their interactions had significant effects on wheat yield,biomass and water use efficiency.N,P and NP addition significantly increased wheat yield,biomass and water use efficiency both in RFM and FP farming system.For wheat yield,N,P and NP under RFM treatment increased by 75.5-80.4%,69.3-90.6%and 116.4-129.6%compared with CK,and N,P and NP addition under FP treatment increased by 76.5-135.3%,100-126.3%and119.3-169.5%,respectively.For water use efficiency,compared with CK,N,P and NP increased by 97.8-101.4%,94.1-114.5%and 155.5-181.3%in RFM system,and increased by 108.1-187%,137.5-179.2%and 208.6-261.3%in FP treatment,respectively.Among all nutrient addition treatments,RFM significantly increased wheat yield,biomass,and water use efficiency compared to CK.7.The effect of nitrogen and phosphorus addition on soil organic carbon soil quality under ridge-furrow with mulching system.N addition significantly decreased while P addition increased CO2 emission,and N and P addition did not affect CO2emission.N addition generally increased DOC and mineralized nitrogen content,led to soil acidification,decreased soil microbial biomass and enzyme activity,which suppressed SOC decomposition.P addition increased the content of DOC and AP,promoted the enzyme to decomposing soil cellulose,glucosamine,polyamine and lignin,decreased the APA,and finally enhanced SOC decomposition.Compared with FP,RFM significantly increased CO2 emission,which was due to the increases in DOC,microbial biomass and enzyme activity.Compared with FP,RFM significantly increased soil soluble carbon,microbial biomass and enzyme activity,thus accelerated soil CO2 emission.In sum,RFM combined mulching wheat straw improved soil hydrothermal conditions,increased the soil water and nutrient use efficiency,so that the better yield effect could be achieved.Meanwhile,it could increase the content of soil organic carbon and slow down the mineralization process of mulching plastic on organic matter,it is an innovative farming practice to improve field sustainable development.Tanken together,dual plastic and straw mulching system,planting density of 220 kg ha-1,ridge-furrow ratio of 1-1.5,ridge-furrow unit size of 40 cm,ridge height of 15cm and rational nitrogen and phosphrous fertilization were the optimum RFM system in semi-arid regions of EAP.It is important in promoting farmland productivity and soil quality,and provides theoretical basis and scientific support for addressing climate change and food security in semiarid EAP.

  • 【Contributor】 兰州大学
  • 【Year of Internet Publish】202101
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