The first factor affecting dryland winter wheat grain yield under various mulching measures: Spike number

Water is the key factor limiting dryland wheat grain yield.Mulching affects crop yield and yield components by affecting soil moisture.Further research is needed to determine the relationships between yield components and soil moisture with yield,and to identify the most important factor affecting grain yield under various mulching measures.A long-term 9-yearifeld experiment in the Loess Plateau of Northwest China was carried out with three treatments:no mulch (CK),plastic mulch (M_(P)) and straw mulch (M_(S)).Yield factors and soil moisture were measured,and the relationships between them were explored by correlation analysis,structural equation modeling and significance analysis.The results showed that compared with CK,the average grain yields of M_(P) and M_(S) increased by 13.0and 10.6%,respectively.The average annual grain yield of the M_(P) treatment was 134 kg ha^(–1) higher than the M_(S) treatment.There were no significant differences in yield components among the three treatments (P<0.05).Soil water storage of the M_(S) treatment was greater than the M_(P) treatment,although the differences were not statistically signifiant.Soil water storage during the summer fallow period (SWSSF) and soil water storage before sowing (SWSS) of M_(S) were significantly higher than in CK,which increased by 38.5 and 13.6%,respectively.The relationship between M_(P) and CK was not statistically significant for SWSSF,but the SWSS in M_(P) was significantly higher than in CK.In terms of soil water storage after harvest (SWSH) and water consumption in the growth period(ET),there were no signi?cant differences among the three treatments.Based on the three analysis methods,we found that spike number and ET were positively correlated with grain yield.However,the relative importance of spike number to yield was the greatest in the M_(P )and M_(S) treatments,while that of ET was the greatest in CK.Suifcient SWSSF could indirectly increase spike number and ET in the three treatments.Based on these results,mulch can improve yield and soil water storage.The most important factor affecting the grain yield of dryland wheat was spike number under mulching,and ET with CK.These findings may help us to understand the main factors influencing dryland wheat grain yield under mulching conditions compared to CK.

Plastic mulch increases dryland wheat yield and water-use productivity,while straw mulch increases soil water storage

Amplifying drought stress and high precipitation variability impair dryland wheat production.These problems can potentially be minimized by using plastic mulch(PM)or straw mulch(SM).Therefore,wheat grain yield,soil water storage,soil temperature and water-use productivity of PM and SM treatments were compared with no mulch(CK)treatment on dryland wheat over a period of eight seasons.Compared to the CK treatment,PM and SM treatments on average significantly increased grain yield by 12.6 and 10.5%,respectively.Compared to the CK treatment,SM treatment significantly decreased soil daily temperature by 0.57,0.60 and 0.48℃ for the whole seasons,growing periods and summer fallow periods,respectively.In contrast,compared to the CK treatment,PM treatment increased soil daily temperature by 0.44,0.51 and 0.27℃ for the whole seasons,growing periods and summer fallow periods,respectively.Lower soil temperature under SM allowed greater soil water storage than under PM.Soil water storage pre-seeding was 17%greater under the SM than under the PM treatment.Soil water storage post-harvest was similar for the PM and SM treatments,but evapotranspiration was 4.5%higher in the SM than in the PM treatment.Consequently,water-use productivity was 6.6%greater under PM than under the SM treatment.Therefore,PM treatment increased dryland wheat yield and water-use productivity,while straw mulch increased soil water storage.

Growth Characteristics and Yield of Late-Season Rice under No-tillage and Non-flooded Cultivation with Straw Mulching

A long-term field experiment （started at 2003） was conducted to determine the effects of different dce cultivation methods on growth characteristics and grain yield of late-season rice under double-rice cropping system in seasonal drought region of southeast China （Yujiang County, Jiangxi Province）. The rice cultivation methods included no-tillage and flooded rice cultivation （N-F）, no-tillage and non-flooded rice cultivation with straw mulching （N-SM）, and no-tillage and non-flooded rice cultivation without straw mulching （N-ZM）. There was no significant difference in rice grain yield between the N-SM and N-F treatments. However, the rice grain yields in the N-SM and N-F treatments were significantly higher than that in the N-ZM treatment. The late-season rice plants in the N-SM treatment had significantly higher numbers of effective panicles and total grains per hill compared with those in the N-ZM treatment. The above-ground dry matter of late-season rice was similar between the N-SM and N-F treatments. Compared with the N-F treatment, the N-ZM and N-SM treatments significantly decreased the leaf area at the heading stage. Moreover, the N-SM treatment could significantly increase total root length and root tip number at the grain-filling stage compared with the N-ZM treatment.

Effects of Non-flooded Cultivation with Straw Mulching on Rice Agronomic Traits and Water Use Efficiency

A field experiment was conducted to study water use efficiency and agronomic traits in rice cultivated in flooded soil and non-flooded soils with and without straw mulching. The total amount of water used by rice under flooded cultivation （FC） was 2.42 and 3.31 times as much as that by rice under the non-flooded cultivation with and without straw mulching, respectively. The average water seepage was 13 560 m^3/ha under the flooded cultivation, 4 750 m^3/ha under the non-flooded cultivation without straw mulching （ZM） and 4 680 m^3/ha under non-flooded cultivation with straw mulching （SM）. The evapotranspiration in the SM treatment was only 38.2% and 63.6% of the FC treatment and ZM treatment, respectively. Compared with the ZM treatment, straw mulching significantly increased leaf area per plant, main root length, gross root length and root dry weight per plant of rice. The highest grain yield under the SM treatment （6 747 kg/ha） was close to the rice cultivated in flooded soil （6 811.5 kg / ha）. However, the yield under the ZM treatment （4 716 kg/ha） was much lower than that under the FS treatment and SM treatment. The order of water use efficiency and irrigation water use efficiency were both as follows： SM〉 ZM〉 FC.

Research on the effect of straw mulching on the soil moisture by field experiment in the piedmont plain of the Taihang Mountains

To reveal the influencing effect of the long-term straw mulching on the soil moisture, this paper employed the field experiment data in 2010 of a typical area of Taihang Mountains plain, observed the soil moisture dynamic regularities under different mulching patterns by virtue of depressimeter and neutron probe, analyzed the characteristics of soil water content and storage in different depths and seasons under the long-term straw mulching. The results showed that the long-term straw mulching can keep the soil moisture conservation of the deep, while decreased the shallow.(1) The long-term straw mulching can changed the type of soil water movement. If no straw mulching, the type is mainly evaporation-infiltration. And with straw mantle the type would change into infiltration. The number of zero flux plane would be reduced or absent.(2) The long-term straw mulching can increase the soil water reserves of the whole soil profile with the depth between 0 cm and 220 cm. But the soil water content of the layer from 30 cm to 80 cm decreased and the soil water content of the layer from 80 cm to 220 cm increased instead., The effect of soil moisture conservation on winter wheat is not obvious;(3) With no straw mulching, the depth of infiltration recharge by rainfall or irrigation is shallower than 80 cm. In a straw mulching, the influence depth is can extend to 120 cm;(4) With no straw mulching, there is a deep layer on the depth of 220 cm between March and June, while this layer will disappear with a long-term straw mulching.

Design and test of the bilateral throwing soil-covering device for straw mulching machine in orchards

Aiming to lack the function of soil covering in the developed orchard straw mulching machine(OSM),a kind of bilateral counter-throwing soil-covering device was developed to eliminate the orchard fire risk caused by the straw layer.The soil-covering device was suspended at the rear of the OSM.Its core component was a pair of throwing wheels installed on both sides of a frame.Hydraulic motors drove the throwing wheels to take soil on-site and cover the straw layer.The adjustment range of the space between the throwing wheels on both sides was 1.4-2.1 m.Based on the analysis of soil-covering quantity,soil-covering width,thickness uniformity of soil layer,and power consumption,the key parameters such as the radius,the number of the vane,and the minimum rotation speed of the throwing wheels were determined.It was proved that the thickness uniformity of the soil layer by bilateral counter-throwing was better than by unilateral,and bottom throwing was better than top throwing.The blade of the soil cutter consisted of a straight blade and a curved blade,and the sliding-cutting angle was 14°-40°.The field test results showed the soil-covering device had good performance with a width of 1.4-2.2 m,a thickness of the soil-covering layer(TSL)of 23.2-40.7 mm,a standard deviation(SD)of 1.4-2.9 mm,width uniformity of 100%,and leakage rate of zero.The established model,between the thickness of soil-covering layer and trenching depth,throwing angle,and rotation speed of the throwing wheels,has a determination coefficient of 0.9757 and can be used to guide the operating parameters.The soil cutter reduced the power consumption and impact load of the throwing wheels by 64.77%and 60.88%,respectively.This work provides a type of new equipment for the mechanization technology of straw mulching in arid and semi-arid orchards.

Improving uniform scattering device for straw-smashing,back-throwing,no-tillage planter under complete straw mulching condition

With the objective of obtaining a completely straw-mulched field,when no-tillage mechanical sowing is implemented with straw smashing,delivering,and back-throwing approaches,it may be difficult to scatter the smashed straw uniformly during a succeeding wheat sowing step.This is because the previous rice straw is substantial in quantity and has a high humidity and toughness,which may easily result in non-uniform straw mulching and thus sparse and weak seedlings of wheat.Therefore a force-dispersing and uniform-scattering device was designed.With the number of scattering impellers,impeller angle,and impeller rotation speed as the main factors and the percentage of pass for the scattering width and non-uniformity of the straw mulching as the assessment indices,single-factor experiments and orthogonal regressive tests were performed,and a dual-index(percentage of pass for the scattering width and non-uniformity of the straw mulching)fitted regression equation was established.The test results suggested that the main factors(from primary to secondary)that influence the indices were the impeller rotation speed,number of scattering impellers,and impeller angle.The optimal parameter combination for the uniform scattering device was four rows of impellers with an angle of 15°,rotation speed of 1015 r/min,percentage of pass of 72.65%for the scattering width,and a non-uniformity of 13.8%in the straw mulching.This combination can be used to realize a uniform scattering of the smashed straw along the seedling rows on the after-sowing ground.According to the field investigation of the wheat growth,the wheat emergence rate was 90.7%.The research results can provide a reference for improving the uniform scattering device for a straw-smashing,back-throwing,no-tillage planter for obtaining a completely straw-mulched field,enhancing the quality of the machinery operation,and ensuring good and strong seedlings after sowing.

Efficiency of potassium-solubilizing Paenibacillus mucilaginosus for the growth of apple seedling

Chemical potassium(K)fertilizer is commonly used in apple(Malus domestica L.Borkh)production but K is easily fixed by soil,resulting in reduced K ferilizer utilization and wasted resources.K-solubilizing bacteria(KSB)can cost-effectively increase the soluble K content in rhizosphere soil.Therefore,the objectives were to select high-efficiency KSB from apple orchards under various soil management models and evaluate their effects on apple seedling growth.Maize(Zea maysL.)straw mulching(MSM)increased the total carbon(TC),total nitrogen(TN)and available potassium(AK)in the rhizosphere and improved fruit quality.The number of KSB in the rhizosphere soil of MSM was 9.5×10×CFU g1 soil,which was considerably higher than that in the other mulching models.Fourteen KSB strains were isolated with relative K solubilizing ability ranging from 17 to 30%,and five strains increased the dry weight per apple seedling.The most eficient strain was identified as Paenibacillus mucilaginosus through morphological observation and sequence analysis of 16S rDNA,named JGK.After inoculation,the colonization of JGK in soil decreased from 4.0 to 1.5×10×CFU g^-1 soil within 28 d.The growth of the apple seedlings and the K accumulation in apple plants were promoted by irigation with 50 mL JGK bacterial solution(1×10^9 CFU mL^-1),but there was no significant increase in the AK content of rhizosphere soil.High-performance liquid phase analysis(HPLC)data showed that the JGK metabolites contained phytohormones and organic acids.Hence,the JGK strain promoted the growth of two-month-old apple seedlings by stimulating function of the produced phytohormones and enhanced K solubility by acidification for apple seedling uptake.This study enriches the understanding of KSB and provides an effective means to increase the K utilization efficiency of apple production.

Ground cover management and farmyard manure effects on soil nitrogen dynamics, productivity and economics of organically grown lettuce (Lactuca sativa L. subsp, secalina)

Ground cover management and farmyard manure （FYM） management have important roles in organic lettuce production. However, there is not enough information about their combined effects. In order to assess the effects of individual and combined ground cover and FYM management on soil mineral N （NH4-N and NO3-N） dynamics, lettuce yield and economics in organic farming, a two-year field experiment was conducted on a certified organic farm in Kisa6 （Vojvodina, Serbia）. The experiment had a two-factorial split-plot completely randomized block design. FYM was applied on the half of the experimental field as a whole-plot factor, while ground cover management included the following four treatments： （I） control, without ground cover management （0）; （11） hoeing （H）; （111） agrotextile cover; （IV） straw mulch （SM）, which were applied on split plots. The applied SM and AT increased soil moisture by 12.83 and 3.73%, respectively, compared to the control treatment. FYM increased soil mineral N concentration, the lettuce fresh matter （FM） yield and nitrate concentration in lettuce. However, nitrate concentration in lettuce in all treatments was below the limit required by the European Commission （EC） （2001）. The highest lettuce yield was obtained by AT （39 122 kg）, followed by SM （33 925 kg）, and it was higher with FYM application by 16.85%. Hoeing did not positively affect the yield, probably due to its negative effect on soil moisture. Additional profit was higher with FYM, showing the following decreasing order： AT〉H〉SM〉Ф. However, value/cost ratio （VCR） was in the order Ф〉H〉SM〉AT on FYM fertilized plots. FYM application led to higher lettuce yield and higher profit and VCR. In case a farm does not have FYM, SM is the best alternative due to its positive effect on the yield and low investment costs. Keywords： hoeing, agrotextile cover, straw mulch, farmyard manure, FYM, mulch

Effects of straw mulching on microclimate characteristics and evapotranspiration of drip-irrigated winter wheat in North China Plain

Field experiments were conducted for two consecutive years(2013-2014 and 2014-2015)to study the effects of straw mulching on microclimate characteristics,energy flux,soil evaporation(Es)and evapotranspiration of winter wheat(Triticum aestivum L.)under adequate drip irrigation in North China Plain(NCP).The results revealed that straw mulching affected air temperature(T_(a))and dew point temperature(T_(d))near the soil surface but had little effect on relative humidity(RH)compared with non-mulched fields.Straw mulching increased the turbulent exchange coefficient(K),and K within the canopy was higher than that above the canopy.Straw mulching clearly increased the sensible heat flux(H)distribution in April-June,and part of the energy needed for evapotranspiration was provided by transfer from the warmer air aloft.There was a linear functional relationship between H and T_(a)measured above and within the canopy.The straw mulching decreased Es but increased crop transpiration(T).Mulched treatment(TM)can decrease the total irrigation amount by about 7%-15%compared with the non-mulched treatment(TN).There were no significant differences(p>0.05)in cumulative crop evapotranspiration(ETc)between TM and TN treatments under adequate drip irrigation,and the use of mulch may need to be combined with an optimal deficit drip irrigation schedule for managing the declining water table in NCP.

Effects of mulch and planting methods on Medicago ruthenica seed yield and soil physical-chemical properties

Medicago ruthenica (L.) Trautv., a wild grass species, is commonly grown as a forage crop in arid and semi-arid areas of China. Herein, we explored mulch patterns and planting methods for optimizing M. ruthenica seed production in the loess plateau of the Gansu Province, China from 2017 to 2019. The experiments comprised of six treatments including (1) flat ground without mulch (F0, control);(2) flat ground with a transparent white 0.008 mm thick plastic film mulch (FP);(3) flat ground with 4500 kg/hm2 straw mulch (FS);(4) furrow with 10 cm ridges (R0);(5) furrow with plastic film mulch (RP);and (6) furrow with straw mulch (RS). Results showed that the harvested seed yield of M. ruthenica was the highest under RP treatment, followed by FP and FS treatments. Soil moisture content from mid-May to mid-August in 2017 was the highest under RP and FP treatments, followed by RS and FS treatments. In 2018, soil moisture content was the highest under RS and FS treatments. In 2017 and 2018, soil temperature was the highest under FP and RP treatments, followed by F0 and R0 treatments. Total and available nitrogen, phosphorus, and potassium contents were the highest under RS and FS treatments, followed by RP and FP treatments. Comprehensive analysis result showed that surface mulch improved soil microenvironment and increased seed yield of M. ruthenica. Straw mulch also effectively recycled excess crop straw, thereby encouraging the sustainable development of agriculture in this area. In conclusion, FS treatment was considered the best mode for M. ruthenica seed production in this area.

Effect of mulching with maize straw on water infiltration and soil loss at different initial soil moistures in a rainfall simulation

Mulching and soil water content(SWC) have a significant impact on soil erosion,and this study investigated the effect of straw mulching on water infiltration and soil loss under different initial SWC treatments in a rainfall simulation experiment conducted in northern China.Increasing initial SWC can decrease soil infiltration and increase soil loss.During an 80 mm rainfall event(80 mm·h–1for 60 min),8%,12% and 16% initial SWC treatments decreased cumulative infiltration by8.7%,42.5% and 58.1%,and increased total sediment yield by 44,146 and 315 g,respectively,compared to 4%initial SWC.However,in all the straw mulching treatments,there was no significant difference in stable infiltration rate between the different initial SWC treatments.For all initial SWC treatments,straw mulching of30% or more significantly enhanced water infiltration by over 31% and reduced soil loss by over 49%,compared to the unmulched treatment.Taking into consideration the performance of no-till planters,a maize straw mulching rate of 30% to 60%(1400–3100 kg·hm–2) is recommended for the conservation of water and soil in northern China.

Soil Fertility Indices of Citrus Orchard Land Along Topographic Gradients in the Three Gorges Area of China

In the Three Gorges Area of China, soil erosion and the resultant non-point source pollution and ecological degradation have endangered agricultural ecosystems and fresh water reservoirs. Although efforts have been undertaken to reduce soil and water losses from slope land used for citrus production, information on the effects of management practices on soil fertility indices is either limited or nonexistent. This study was conducted to compare the effects of 10 years of various management practices, citrus intercropped with white clover (WC), citrus mulched with straw (SM), citrus intercropped with contour hedgerows (CH), citrus orchard land with impermeable membrane (IM), and citrus intercropped with wheat (Triticum aestivum) and peanut (Arachris hypogaea) (WP), as treatments on soil fertility indices with that of the conventional citrus management (CM). Results showed that the soil organic carbon, total and available nitrogen, available potassium, and water-stable aggregate (> 0.25 mm) contents at the 0–5 cm depth were higher for the WC and SM treatments than the CM treatment. There was also spatial variation in soil fertility along slopes of the WC and SM treatments. The soil total and available nitrogen, phosphorus, and potassium, and water-stable aggregate (> 0.25 mm) contents at both the 0–5 and 5–20 cm depths were higher for the CH and IM treatments than the CM treatment. The average soil available nitrogen and available potassium contents were higher for the WP treatment than the CM treatment, but the WP treatment had little effect on the soil organic carbon, total nitrogen, and water-stable aggregate (> 0.25 mm) contents. These suggested that white clover intercropping and straw mulching were the most effective approaches to improve soil fertility in citrus orchard land of the Three Gorges area.

Protection Methods to Reduce Nitrogen and Phosphorus Losses from Sloping Citrus Land in the Three Gorges Area of China

The increased application of chemical fertilizers in citrus orchards and the non-point source nitrogen(N) and phosphorus(P)diffusion threaten the fresh water quality of the Three Gorges Reservoir area of China. A 10-year field trial on sloping citrus lands was conducted to evaluate five protection methods for reducing N and P losses: 1) intercropping with perennial white clover(CW); 2) straw mulching of the soil surface(CS); 3) intercropping with yellow daylily contour hedgerows(CH); 4) an impermeable membrane buried in the soil along the contour lines(CM); and 5) intercropping with a rotation of wheat and peanut(CWP). An area of conventional citrus management was also maintained as the control(CK). The results showed that CM and CH were the most effective methods for reducing surface runoff. The sediment yield were reduced at the highest rate by CW and CH and was also significantly reduced by CS. Reduced runoff volume and sediment yield were the crucial mechanism for the reductions in N and P losses. Compared with the control, CW, CS, CH, and CM reduced annual runoff by 9%, 13%, 25%, and 30%, sediment yield by 77%, 55%, 71%, and 28%,N loss by 10%, 23% 36%, and 37%, and P loss by 39%, 31%, 27%, and 25%, respectively. CW, CS, CH, and CM were effective in reducing N and P losses from the sloping citrus land. However, over the long-term, surface soil nutrient accumulation in CW, CS, and CH diminished the benefit of those methods in reducing N and P losses. In addition, CWP increased soil erosion and nutrient loss,which showed that citrus intercropping with other crops was an unsuitable method for citrus sloping land in the Three Gorges area.

Improving water use ef fi ciency in grain production of winter wheat and summer maize in the North China Plain: a review

Reducing irrigation water use by improving water use ef ficiency(WUE) in grain production is critical for the development of sustainable agriculture in the North China Plain(NCP). This article summarizes the research progresses in WUE improvement carried out at the Luancheng station located in the Northern part of NCP for the past three decades. Progresses in four aspects of yield and WUE improvement are presented, including yield and WUE improvement associated with cultivar selection, irrigation management for improving yield and WUE under limited water supply, managing root system for ef ficient soil water use and reducing soil evaporation by straw mulch. The results showed that annual average increase of 0.014 kg$m^(–3)for winter wheat and 0.02 kg$m^(–3)in WUE were observed for the past three decades, and this increase was largely associated with the improvement in harvest index related to cultivar renewal and an increase in chemical fertilizer use and soil fertility. The results also indicated that de ficit irrigation for winter wheat could signi ficantly reduce the irrigation water use, whereas the seasonal yield showed a smaller reduction rate and WUE was signi ficantly improved. Straw mulching of summer maize using the straw from winter wheat could reduce seasonal soil evaporation by 30–40 mm. With new cultivars and improved management practices it was possible to further increase grain production without much increase in water use. Future strategies to further improve WUE are also discussed.

Effect of Conservation Tillage Practices on Soil Phosphorus Nutrition in an Apple Orchard

Soil phosphorus(P) is an essential and limiting element for plant growth, which is significantly affected by different approaches to soil management. In order to reveal the effect of different management approaches on soil P and phosphatase activity in 0–20 cm and 20–40 cm soil, this research was conducted to study variations in the characteristics of P and phosphatase activity under 3-year tillage without mulching(CK), notillage with corn straw mulching(NTSM) and no-tillage with grass(NTG) in Liaoning apple orchard. The results showed that NTSM and NTG could significantly increase soil P content(P < 0.05) as compared with CK. However, the effect was different between NTSM and NTG; with the NTSM approach, the improvement in the P content in 20–40 cm was remarkable, and in the NTG approach, the improvement in the soil surface P content was significant. At the same time, soil phosphatase activity significantly increased(P < 0.05) under NTSM and NTG. The soil surface and 20–40 cm phosphodiesterase(PD) activity was enhanced under the two management approaches, however, the effect of NTG was stronger than NTSM. In addition, NTSM was more conducive to increasing alkaline phosphomonoesterase(Al P), and NTG was more conducive to increasing acid phosphomonoesterase(Ac P). Our findings highlight the variation of dominant mechanisms involved in soil P with different mulching materials application. NTSM and NTG could have the potential to increase P content and phosphatase activity, and provide a basis for using this method to improve P phytoavailability and reduce the application of soil fertilizer.