Film fully-mulched ridge-furrow cropping affects soil biochemical properties and maize nutrient uptake in a rainfed semi-arid environment

Abstract

This study evaluated the effects of plastic mulched ridge-furrow cropping on soil biochemical properties and maize (Zea mays L.) nutrient uptake in a semi-arid environment. Three treatments were evaluated from 2008 to 2010: no mulch (narrow ridges with crop seeded next to ridges), half mulch (as per no mulch, except narrow ridges were mulched), and full mulch (alternate narrow and wide ridges, all mulched with maize seeded in furrows). Compared to the no mulch treatment, full mulch increased maize grain yield by 50% in 2008 and 25% in 2010, but reduced yield by 21% in 2009 after low precipitation in early growth. Half mulch had a similar grain yield to no mulch in the three cropping years, suggesting half mulch is not an effective pattern for maize cropping in the area. Mulch treatments increased aboveground nitrogen (N) uptake by 21?34% and phosphorus (P) uptake by 21?42% in 2008, and by 16?32% and 14?29%, respectively, in 2010; but in 2009 mulching did not affect N uptake and decreased P uptake. Soil microbial biomass and activities of urease, β-glucosidase and phosphatase at the 0?15 cm depth were generally higher during vegetative growth but lower during reproductive growth under mulch treatments than no mulch. Mulching treatments increased carbon (C) loss of buried maize residues (marginally by 5?9%), and decreased light soil organic C (15?27%) and carbohydrate C (12?23%) concentrations and mineralizable C and N (8?36%) at harvest in the 0?20 cm depth compared with no mulch, indicating that mulching promotes mineralization and nutrient release in soil during cropping seasons. As a result of these biological changes, mineral N concentration under mulch was markedly increased after sowing in upper soil layers compared with no mulch. Therefore, our results suggest that mulched cropping stimulated soil microbial activity and N availability, and thus contributed to increasing maize grain yield and nutrient uptake compared with no mulch.     

Exploring optimal soil mulching to enhance maize yield and water use efficiency in dryland areas in China

Water and nutrient availability significantly limits global crop production, especially for dryland agriculture in arid and semi-arid regions. To explore the optimal soil mulching options for the Loess Plateau in China, a 3-year field study was conducted to investigate the effects of various soil mulching practices on soil temperature and the water use and grain yield of spring maize. The treatments included traditional flat farming (CK), narrow plastic film mulch (NM), wide plastic film mulch (WM) and narrow plastic film mulch?+?maize straw mulch between rows (MS). The results showed that MS treatment increased consistently soil temperature during the initial stages of maize growth, and more importantly, it reduced diurnal temperature variation. MS also increased in soil water storage by 10.1%, leading to the highest water use efficiency (WUE?=?30.9?kg?ha^?1?mm^?1) over CK on 3 year average. MS significantly increased maize yield and net income of farmers by up to 20%, compared to CK. In conclusion, optimisation of soil mulching strategies significantly enhanced crop yield and water productivity in dryland agriculture in China. Our study provides important guidance for exploring better soil management practice for dryland agriculture in the other regions of the world.     

Effects of vegetative mulches on growth of indigenous crops in the Kingdom of Tonga

As in many areas of the developing world, intensification of agriculture in Tonga, and other Pacific Islands, has put increased pressure on the soil resource. Two experiments were conducted to evaluate the effect of mulch on the growth and yield of two important food and fibre crops. The first was conducted on sloping land to evaluate the effect of guinea grass (Megathyrsus maximus ) mulch and hedgerows on taro [Colocasia esculenta (L.) Schott] yield, and in controlling soil erosion. The second compared the response of paper mulberry [Broussonetia papyrifera (L) Ventenot] to different management regimes of a grass fallow. Thick vegetative mulch increased taro corm yield by 81% and reduced soil loss by 50% compared to local farmer practice, and the soil loss from taro with mulch was comparable to the perennial cash hedgerow treatment. Mulch increased paper mulberry bark yield by 30% compared to the non‐mulch control. Comparative economic analysis showed that increased net profit in the mulched treatments compared to the non‐mulched control was T$2660/ha for taro and T$12 108/ha for paper mulberry. Considering that mulch is readily available to many farmers throughout the Pacific Islands and elsewhere in the tropics, it is recommended as a sustainable practice for crop production.     

玉米二元覆盖农田水分动态及水分利用效率研究

旱地玉米采用垄面覆膜、垄沟覆不同用量麦草的二元覆盖试验结果表明:随麦草覆盖量的增加土壤保墒效果明显;其中0~100cm土层土壤玉米全生育期累积贮水量5250kg/hm2和9750kg/hm2的麦草覆盖处理比垄面覆膜垄沟未覆麦草处理平均增加146.2mm,水分利用效率提高16.67%~28.65%,降水利用率提高12.39%~18.29%,玉米增产12.10%~18.15%。     

Soil physical changes and maize growth in a structurally fragile tropical soil due to mulching and duration between irrigation intervals

Under tropical meteorological conditions, the volume of soil explored by plant roots is crucial for crop growth as it allows increased water and nutrient use efficiency. We hypothesized that, under different irrigation intervals, leguminous mulch can extend the duration between irrigation events but maintain crop performance, because decreased evaporative fluxes also reduce constraints to root exploration imposed by mechanical stress. We evaluated the combined effects of leguminous mulch and irrigation intervals on soil physical properties to determine whether the growth and productivity of maize were modified in a structurally fragile tropical soil. The experiment involved the following treatments: 4‐day irrigation intervals with soil mulched (4C) or bare (4S), 6‐day irrigation intervals with soil mulched (6C) or bare (6S), 8‐day irrigation intervals with soil mulched (8C) or bare (8S) and 10‐day irrigation intervals with soil mulched (10C) or bare (10S). Mulch decreased soil penetration resistance and increased to 4 days the favourable time for root development in drying soil. Relative to bare soil, mulch with a 6‐day irrigation interval almost doubled nitrogen uptake post‐tasselling, which decreased nitrogen remobilization and increased the crop growth rate during this stage. These conditions had a positive effect on the transpiration rate and stomatal conductance as well as on the growth and yield of maize. A 6‐day irrigation interval with mulch compared to 4 days with bare soil resulted in similar conditions for root development, but greater uptake of nitrogen (102.73–78.70 kg/ha) and better yield (6.2–5.3 t/ha), which means greater efficiency in nitrogen and water use.     

Modelling the impacts of maize decomposition on glyphosate dynamics in mulch

The retention of crop residues as mulch on the soil surface in conservation agriculture systems greatly influences the fate of pesticides, as most of the applied pesticide is intercepted by mulch before moving to the soil. This work was conducted in order to model the effect of maize decomposition on glyphosate degradation in mulch and soil. Labelled ¹⁴C‐glyphosate degradation was monitored for 49 days in three treatments with the same soils but with maize residues at different stages of decomposition (0, 20 and 49 days). Fresh residues of maize (0 days) exhibited an evolution of their biochemical fractions to a greater extent than decomposed residues. Glyphosate mineralization was faster in the 0‐day treatment in mulch residues and in the soil layer below the mulch. However, a greater formation of non‐extractable residues (NERs) was observed in mulch residues and soils in the 20‐ and 49‐day treatments than in the 0‐day treatment. Modelling maize mulch decomposition with the COP‐soil model indicated that microbial activity was different in the three treatments and depended on the initial composition of maize residues. Glyphosate mineralization in mulch and soil can be simulated with an assumption of co‐metabolism by coupling the modules of pesticide degradation and mulch carbon decomposition. Glyphosate and its metabolites, including soluble and adsorbed fractions, were simulated with the same adsorption coefficients for all treatments. The simulation of NER formation, however, suggested that more than one microbial population may be involved in the degradation process and could be added in the future development of the model.     

地表覆盖方式对辣椒水分利用效率、果实品质及氮素分布的影响

研究了地表覆盖方式对辣椒 (Capsicum anmuum L.)水分利用效率、品质、叶片硝酸还原酶活性及植株和土壤中氮素分布的影响。结果表明,覆盖可增加辣椒整个生育期土壤水分含量。覆盖地膜和覆盖秸秆+地膜比其他地表处理方式能显著增加辣椒的产量和经济收入,提高产量水分利用效率和经济水分利用效率。覆盖可显著降低耕作层（0—20 ㎝）土壤硝态氮含量,且随着土层深度的增加,硝态氮含量显著降低,但对各土壤铵态氮含量无显著影响。对品质而言,覆盖地膜处理辣椒果实pH、维生素C含量显著高于其它处理,且其电导率、阳离子交换量和硝酸盐含量显著低于其他处理。覆盖可增强叶片硝酸还原酶活性,降低叶片中的全氮含量,显著降低每百千克产量氮肥吸收量。从提高辣椒的品质、环境安全、肥料利用和经济效益各因素考虑,生产中辅以科学的水分管理,覆盖地膜和覆盖秸秆+地膜是可行的地表覆盖方式。     

Photosynthesis,growth, and fruit yield of cucumber in response to oxo-degradable plastic mulches

The use of plastic mulch is associated with a higher increase in yield of vegetables. However, at the end of the growing season for each crop, plastic mulching can create environmental pollution that can cause negative impacts on the environment that could be solved by the use of degradable plastics. The aim of this study was to determine the effect of oxo-degradable plastic mulches on soil temperature, growth, gas exchange, and cucumber crop yield. The study was conducted in two locations in the northeast of Mexico during the spring and summer of 2013. The plastic mulch colors with additives were blue, green, and red and each color having 8% and 12% of pigment and 22% and 23% of Titanium dioxide (Rutile). The resultant treatments were compared with the black plastic mulch, which is the standard plastic in the world, and bare soil in a randomized complete block design with three replications in two locations. The mean soil temperature at both locations was statistically higher in black plastic mulch, followed by the oxo-degradable plastics mulches and lowest in the control. Gas exchange was not affected by plastic mulches. SPAD units as the index of chlorophyll content in leaves were very little affected by plastic mulch. Both, commercial and total yield were statistically similar in the oxo-degradable plastic mulches and the black plastic mulch, and lowest in the control. Plastics with higher concentrations of pigment registered higher degradation in both locations. Our results suggest that different plastic mulches impact positively on the yield of cucumber crop. The benefit in yield by the different plastic mulches in the conditions of this study was due to their soil warming ability that results in improved soil temperature, leaf area, and plant dry weight.     

砾石覆盖对土壤水热过程及旱作小麦玉米产量的影响

为了揭示砾石覆盖对农田土壤水热变化及作物产量形成的影响,2013—2015年采用小区试验法研究冬小麦-夏玉米轮作条件下土壤水分变化、温度效应以及作物生长和产量之间的相互作用关系。田间试验设置无覆盖(CK)、25%砾石覆盖(GM1)、50%砾石覆盖(GM2)、75%砾石覆盖(GM3)和100%砾石覆盖(GM4)5个处理。结果表明:砾石覆盖度与土壤水分呈显著正相关,100%砾石覆盖处理土壤贮水量最高;干旱胁迫条件下砾石覆盖度越高土壤的保水性越好,降雨条件下砾石覆盖度越高土壤截留雨水的能力越大。砾石覆盖具有明显的增温效应,4个砾石覆盖处理的土壤平均温度大于CK处理,GM4处理土壤平均温度最大;砾石覆盖处理可以认为是一种有效的温度调节方式,具体表现在低温(-5~0℃)条件下GM4处理较CK处理土壤温度增加5℃,高温(40~45℃)条件下GM4处理较CK处理土壤温度降低3.7℃;在寒冷气候和水分亏缺的情况下4个砾石覆盖处理增温能力均大于对照。此外,夏玉米叶面积指数随着砾石覆盖度增加而增大。100%砾石覆盖处理的2季冬小麦和夏玉米平均产量较对照处理分别增加了58.55%和22.50%。可见,砾石覆盖技术可以有效保持土壤水分、增加土壤温度、促进作物生长和提高产量,是干旱半干旱地区应对水分胁迫和气候变化、     

Changes induced by plastic film mulches on soil temperature and their relevance in growth and fruit yield of pickling cucumber

Purpose: The aim of this study was to realize whether soil mulching, with different plastic mulch colors, is a suitable practice for the culture of pickling cucumber.

Materials and Methods: The crop was cultured or not with black, silver/black, white/black, and aluminum/black plastic films, treatments were evaluated in randomized complete block design, to determine their effect on soil temperature, gas exchange, nutrient concentration, growth, and fruit yield.

Results and Conclusions: Black, silver/black, and aluminum/black plastic mulches were higher (p?≤?0.05) in plant height, leaf area, and shoot dry weight than bare soil at 15 days after sowing, whose results were similar than using white/black film. Maximum, minimum, and mean soil temperatures were higher with all plastic mulches except for aluminum/black, in which the maximum soil temperature was similar to the one in bare soil. There was no difference in net photosynthesis and there was very little difference in nutrient concentration between plants in plastic mulches and plants in bare soil; however, early and total yield showed a higher (p?≤?0.05) yield in all plastic mulches, and lower with bare soil and white/black plastic mulch. Our results confirm that soil mulching impacts the pickling cucumber yield. We suggest a carefull selection of the color plastic mulch.     

多年采用不同捡拾方式对地膜残留系数及玉米产量的影响

随着地膜用量和覆盖面积的不断增加,在作物产量提高的同时,田间残膜残留量也随之增加,加剧了农业地膜污染。本论文以连续4年(2011—2014)长期定位试验为依托,探明完全捡拾、常规捡拾及不捡拾3个处理对地膜残留量、残留系数及玉米产量的影响。结果表明:0~10 cm土层地膜残留最多,不捡拾处理残膜量显著高于常规捡拾,完全捡拾与常规捡拾差异不显著;10~20 cm土层地膜残留量其次,不捡拾处理残膜量与常规捡拾差异不显著,完全捡拾则显著少于常规捡拾;20~30 cm土层地膜残留最少,处理间差异不显著;0~30 cm土层,完全捡拾处理下,面积25 cm~2、4~25 cm~2中大块残膜片数显著少于常规捡拾和不捡拾处理,而面积4cm~2残膜片数与常规捡拾和不捡拾差异不显著;2014年玉米收获后,常规捡拾、完全捡拾及不捡拾处理下地膜残留量分别为80.85、52.71 kg·hm~(-2)及152.65 kg·hm~(-2),地膜残留系数分别为8.53%、-9.45%及54.42%;3种捡拾处理对玉米茎粗、穗长、穗粗、穗行数、行粒数及百粒重均有影响,随捡拾度增加,各指标均呈增加趋势;与常规捡拾相比,不捡拾处理下4年平均减产15.08%,完全捡拾处理下平均增产4.70%。综合分析不同捡拾方式对地膜残留量、残留系数及玉米产量的影响,建议在没有适宜的残膜回收机械的情况下,应采用农民常规捡拾方式,但从长远发展来看,须尽快研发推广适宜的残膜回收机械。     

耕作措施对土壤特性及作物产量的影响

通过夏玉米田间试验研究了不同耕作措施及秸秆覆盖对土壤特性、水分状况、作物产量及水分利用效率的影响。试验处理包括常规耕作、深松、秸秆覆盖、垄作、浅坑及免耕。结果表明,秸秆覆盖可显著提高土壤蓄水量、作物产量及水分利用效率。其保水增产效果在干旱年份更加明显。深松可有效打破犁底层降低其密度,可增加作物根深、根长及根重,提高作物产量和水分利用效率。免耕可提高夏玉米早期田间土壤含水率,保持相同产量。     

免耕覆盖还田下玉米秸秆氮素的去向研究

采用田间微区试验,以15N标记的玉米秸秆为研究对象,研究了免耕覆盖还田下玉米秸秆氮素经过4个生长季后的作物累积利用率、在土壤(0~60 cm)的残留率以及损失情况。试验共设2个处理:TS1为第1年15N标记秸秆覆盖还田,此后秸秆不还田;TS2为第1年15N标记秸秆覆盖还田,此后每年以非标记秸秆还田。结果表明:经过4个生长季后,两个处理间的玉米籽粒、秸秆的累积产量及总氮素吸收量的差异均不显著。在TS1处理中,秸秆氮素在籽粒和秸秆中的累积回收率分别为14.2%和6.7%,并分别高于TS2处理的12.4%和5.8%。与作物的累积回收率相比,更多的秸秆氮素被保持在土壤中。在TS1和TS2处理中,秸秆氮素在土壤中的残留率分别为40.9%和73.8%,而损失率分别为38.6%和8.1%。与TS1处理相比,TS2处理中较高的土壤微生物生物量碳和氮以及较低的矿质态秸秆氮的含量,说明连续秸秆还田在一定程度上提高了最初还田秸秆氮素在土壤中的微生物固持并降低了秸秆氮素的淋失风险,从而显著提高秸秆氮素在土壤-植物系统中的总回收率。因此,在温带农田生态系统中,长期的免耕结合秸秆覆盖还田可促进秸秆氮素的积累,这对提高和保持土壤氮素含量和稳定性具有重要的意义。     

Effects of cover crops,compost, and manure amendments on soil microbial community structure in tomato production systems

Soil microbial community structure and crop yield was investigated in field tomato production systems that compared black polyethylene mulch to hairy vetch mulch and inorganic N to organic N. The following hypotheses were tested: (1) hairy vetch cover cropping increases crop yield and significantly affects soil microbial community structure when compared to the standard plastic mulch and synthetic fertilizer-based system; (2) within plastic mulch systems, organic amendments will increase crop yield and significantly affect soil microbial community structure when compared to synthetic fertilizer; (3) crop yields and microbial community structure will be similar in the hairy vetch cover cropping and the organic amended plasticulture systems. Treatments consisted of ammonium nitrate (control), hairy vetch cover crop, hairy vetch cover crop and poultry manure compost (10 Mg/ha), three levels of poultry manure compost (5, 10, and 20 Mg/ha), and two levels of poultry manure (2.5 and 5 Mg/ha). Black polyethylene mulch was used in all treatments without hairy vetch. Fatty acid analysis was used to characterize the total soil microbial community structure, while two substrate utilization assays were used to investigate the community structure of culturable bacteria and fungi. Crop yield was not significantly increased by hairy vetch cover cropping when compared to black polyethylene mulch, although microbial community structure was significantly affected by cover cropping. Under black polyethylene mulch, crop yields were significantly increased by the highest levels of compost and manure when compared to inorganic fertilizer, but there was no detectable effect on soil microbial community structure. When cover cropping was compared to organic amended plasticulture systems, crop yields were similar one year but dissimilar the next. However, hairy vetch cover cropping and organic amendments under black plastic mulch produced significantly different soil microbial community structure.     

液体地膜对滴灌棉花生理特性和产量的影响

为探寻解决干旱区棉田日益严重的"白色污染"问题的途径,明晰液体地膜代替塑料薄膜与滴灌结合对棉花生理特性与产量的影响效果,通过桶栽试验,设置了5种处理(液体地膜1 900 kg/hm2,LFD1;液体地膜2 200 kg/hm2,LFD2;液体地膜2 500 kg/hm2,LFD3;普通塑膜,PFD;裸地对照,CK),监测和分析了不同处理对滴灌棉花叶片净光合速率、蒸腾速率、气孔导度、胞间CO2浓度、水分利用效率和产量的影响。结果表明,液体地膜覆盖用量的大小对滴灌棉花叶片净光合速率、蒸腾速率、气孔导度、胞间CO2浓度等生理特性指标和水分利用效率及产量均具有重要影响。随着液体地膜用量的增加,滴灌棉花叶片净光合速率、蒸腾速率、气孔导度、胞间CO2浓度及产量也不断增加,并与塑料地膜覆盖处理的差距变小。液体地膜覆盖对滴灌棉花生理特性的影响作用效果在棉花生理活动旺盛的生育前期和中期更为显著,随着作物生育期的推进(液体地膜覆盖时间的延长)而逐渐降低。在所有观测时间点,3个液体地膜覆盖处理的滴灌棉花叶片净光合速率均高于CK且与CK具有显著性差异(P0.05);在不同阶段和同一阶段的不同观测时段不同用量液体地膜处理对棉花叶片净光合速率均具有不同的影响。在棉花生理活动相对旺盛的蕾期6月26日14:00,LFD1、LFD2和LFD3的叶片净光合速率较CK分别提高11.12%、29.76%和40.20%,较PFD分别降低24.96%、12.38%和5.33%;液体地膜覆盖滴灌棉花水分利用效率、单株铃数、单铃质量、产量等指标均高于CK处理(P0.05),液体地膜用量最大的LFD3处理与PFD处理的水分利用效率、单株铃数、单铃质量、产量均没有显著性差异(P0.05)。LFD1、LFD2和LFD3较CK分别增产7.10%、11.79%和14.39%。不同用量的液体地膜覆盖处理对于滴灌棉花水分利用效率及产量具有重要影响,液体地膜通过不断对棉花生理特性的影响最终影响到水分利用效率与产量;适量液体地膜(不低于2 500 kg/hm2)与滴灌结合可以与塑料地膜膜下滴灌棉花具有相当的节水、增产效果(与CK相比),液体地膜具有的可降解、无污染特点将使该技术具有较大的应用潜力。     

Soil management options for Alfisols in the semi-arid tropics: annual and perennial crop production

A field experiment was conducted in the semi arid tropics to study the effects of soil structural modification on cropping systems. The aim was to improve crop production and land resource protection using innovative soil management practices. Tillage, mulch and perennial/annual rotational based systems were compared for 5 years in an Alfisol at ICRISAT in India. Crop yield parameters, including grain and biomass yield, leaf area index, crop cover, and plant height were measured. Results indicate significant benefits to annual crop yield (maize, sorghum) from improved water supply due to mulching with farmyard manure or and rice straw, and due to rotation with prior-perennial crops. Grain yields were 16 to 59% higher in mulched treatments compared to unmulched treatments, with similar increases for fodder yields. Annual crop yields after 4 years of perennials were 14 to 81% higher than unmulched treatments, except for low fertility maize grown after buffel grass. The interaction with chemical fertility was less clear than for water supply. The results have implications for soil management throughout the semi-arid tropics.     

Influence of municipal compost on temperature, water, nutrient status and the yield of maize in a temperate soil

Abstract. Composted domestic waste was applied either as a mulch or was incorporated into the topsoil. Mulching reduced the seasonal midday soil temperature ranges from between 14 °C and 27.5 °C to between 14 °C and 26 °C, averaging a 0.6 °C fall. However, at sub-optimal temperatures for maize production under the temperate conditions of South East England, the difference may be critical. Compost mulch also improved soil-water conservation in an average year, but not in a very dry year. Compost application increased soil-available N, but increased K uptake was considered to be more important for crop yield than either N additions or the effect on retained soil water. Overall, compost applied as a surface mulch, or incorporated into medium-textured soils in the south and east of England increased crop yield.     

不同微生物菌剂对旱砂田西瓜生长和微生物区系的影响

为解决连作旱砂田西瓜植株生长性能、产量品质、根际微生物数量下降的问题,以陇科12号为指示品种,设置常规施肥、常规施肥+西瓜专用菌剂、常规施肥+激活土壤专用菌剂、常规施肥+胶质芽孢杆菌、常规施肥+枯草芽孢杆菌、常规施肥+地衣芽孢杆菌、常规施肥+金宝贝微生物菌剂共7个处理,研究了不同微生物菌剂对旱砂田西瓜出苗与成活率、干物质积累、产量品质和根际微生物区系的影响。结果表明,与对照常规施肥相比,尽管施用微生物菌剂对西瓜果实的含糖量无显著影响,但除常规施肥+激活土壤专用菌剂外,其他微生物菌剂的施用均可以提高西瓜成活率和产量,促进干物质积累,增加西瓜根区微生物数量。其中以常规施肥+地衣芽孢杆菌处理的西瓜出苗率、成活率和产量最高,与对照常规施肥比较,出苗率显著提高7百分点;成活率显著提高了14%;产量显著提高了35.98%。团棵期和开花坐果期的干物质积累量也较对照分别显著增加了28.30%和24.01%,干物质转运量和转运率分别显著增加了3.98倍和3.01倍,根区细菌、真菌和放线菌数量分别显著增加61.07%、84.84%、85.31%。因此,生产上可以常规施肥+地衣芽孢杆菌作为最佳施肥方案,有助于改善旱砂田西瓜根际微生物环境,提高作物产量。     

Effects of Different Irrigation Regimes and Mulches on Yield and Macronutrition Levels of Drip-Irrigated Cucumber Under Open Field Conditions

ABSTRACT

The effectiveness of different mulch types on fruit yield, leaf-nutrient composition, and normal plant growth parameters was investigated in order to maximize water use efficiency (WUE) in cucumber grown under water stress. Treatments were (1) bare soil + water stress (WS), (2) bare soil + unstressed (control, C), (3) black polyethylene mulch + water stress (BPM + WS), (4) wheat straw mulch + water stress (WSM + WS), and (5) wheat straw mulch plus black polyethylene mulch + water stress (WSM + BPM + WS). Seasonal crop evapotranspiration was between 492 and 960 mm. Seasonal irrigation water amounts were 965 and 485 mm for the C and WS treatments, respectively. The WUE ranged from 3.40 to 5.78 kg m^?3, while irrigation water-use efficiency (IWUE) was between 3.39 and 6.08 kg m^?3. IWUE and WUE were increased under WS treatments with mulching compared with the control treatment, as mulching significantly reduced the amount of irrigation water required. Both BPM and WSM improved the fruit yield, fruit size, plant dry matter, total leaf area, and chlorophyll and nutrient concentrations in leaves under the stressed treatments, while these two mulches in combination (BPM + WSM) caused further increases in these parameters. This study confirms that limiting soil evaporation with mulches is a key action to take to save irrigation water and to improve WUE and IWUE. Because use of drip irrigation with mulching can increase WUE, this strategy might be used for vegetable production in semi-arid regions where irrigation water is limited.     

砾石覆盖农田土壤酶活性的动态变化特征

在不同时期采集了砾石覆盖,未覆盖连作西瓜农田和撂荒地的表层土壤,测定了土壤中主要微生物数量和过氧化氢酶、淀粉酶、多酚氧化酶及脱氢酶酶活性,并研究了作物生育期内土壤酶活性的变化特点。结果表明,砾石覆盖处理的农田土壤微生物数量处于较低水平,其真菌数量发生了显著下降,而细菌和放线菌数量则介于未覆盖农田和撂荒地之间。在整个生育期内,不同处理下土壤酶活性变化显著不同,但多在西瓜生长旺盛的抽蔓期和结果期达到极值。作物生长和砾石覆盖对于酶活性的影响作用很大,这为进一步研究砾石覆盖对农田土壤环境影响的机理及砾石覆盖科学管理提供基础依据。