| The rain-fed agricultural region in the Loess Plateau is characterized by low and unstable precipitation,large evaporation,also suffering the serious soil erosion and degradation of cultivated land.How to deal with the serious shortage of production capacity and natural rainfall utilization capacity is a realistic problem that attracts much attention in the Northwest Agricultural Circle.In semi-arid farming area,ridge-furrow mulching farming system of maize has achieved remarkable effect of increasing yield and income.However,the Loess Plateau has a large geographical span and many phenological areas,so the response of different phenological areas to ridge and furrow mulching farming system is also diversified.At present,most studies mainly focus on semi-arid farming areas,ignoring the unique productive potential of agriculture in semi-humid and drought-prone farming areas.Can ridge and furrow mulching farming system be applied in semi-humid farming areas and increase the yield and efficiency?What is the impact of different ridge and furrow tillage patterns on it?What is its physiological and ecological mechanism?These are not only basic scientific issues,but also the regional extension and system upgrading of ridge and furrow mulching farming system.They are also the major demand for the implementation of the targeted poverty reduction strategy for small-scale farmers under rain-fed agriculture in the Loess Plateau.On the basis of many years’domestic research,field experiments and technical validation were carried out with ridge-furrow mulching farming system as the core and various traditional planting modes as reference,including furrow mulching ridge planting（MRM）,whole plastic-film mulching on double ridges and planting（WRF）,ridge and furrow straw mulching（SM）,flat whole mulching（WM）,flat half-film mulching（HM）,no ridges and films（CK）.Field experiments were conducted at provincial dry agriculture demonstration site at Shitougou,Yuzhong County,Gansu Province,in the semi-arid farming area of the Loess Plateau from 2015 to 2016.The parameters,including water dynamics of soil profile,soil temperature,crop water utilization,soil organic carbon,total nitrogen,total phosphorus,available nutrients,enzyme activities,microbial quantities,crop phenological characteristics,growth parameters and biomass distribution patterns,yield and formation factors,water use efficiency and other parameters were systematically collected and analyzed.Firstly,the mechanism of two different types of ridge and furrow film mulching technology in improving spring maize productivity and soil environment ecology in semi-arid farming area of the Loess Plateau was revealed.Secondly,in order to further confirm the efficiency of ridge and furrow plastic film mulching technology in other phenological areas,a validation experiment was carried out in Zhujiapo Agricultural Technology Extension Center,Huating City,Gansu Province,from 2017 to 2018.The water and heat of soil,nutrient balance,enzyme activity,microbial quantity reproduction,crop phenological pattern,yield and water use efficiency and other indicators were comprehensively analyzed,in order to clarify the mechanism of ridge and furrow mulching tillage mode to yield increase,income increase and efficiency increase of dryland maize,further analyze whether the technical system has the potential of sustainable development,and explore the best ridge and furrow mulching tillage mode in semi-arid and semi-humid farming areas,so as to provide theoretical basis and technical support for further research and extension of the technical system in the future.The main conclusions are as follows:1.Ridge and furrow mulching redistributed the water resources in time to balance crop water demand and soil water supply.Spatially,the relationship between crop water demand and soil water supply was optimized,which made it easier for crops to use deep soil water to meet their growth needs,thus increasing the soil water availability.MRM,WRF and SM in semi-arid farming area significantly increased the water storage capacity of the middle layer of soil in growing season by 17.77%,11.61%and 4.39%compared with CK.The accumulation of middle layer of soil provided support for the acquisition of growth moisture in later period of maize,but it did not show the advantage of water storage in semi-humid farming area.The water consumption of spring maize in semi-arid area mainly depended on the precipitation during growth period and soil moisture before sowing.The precipitation consumption during MRM,WRF and SM growth period accounted for 79.07%,80.01%and90.90%of the total water consumption,respectively.The water consumption of spring maize in semi-humid area mainly depended on the precipitation during growing period,which meant that the precipitation during growing period in semi-humid area can not only meet the water demand of crops,but also supply soil water storage.MRM,WRF and SM can supply 3.33,4.34 and 5.70 mm of soil water through ridge and furrow rainwater harvesting.2.The selective application of ridge and furrow mulching materials could realize the seasonal active regulation of soil heat balance,at the same time,there were double effects of increasing temperature and decreasing temperature.The warming effect of film mulching was greater than that of cooling effect,while the effect of straw mulching was the opposite.In the early stage of crop growth,the soil temperature was increased by surface mulching,but under high temperature stress in the middle growing period,the soil temperature was effectively reduced and the harm of high temperature and dry heat was alleviated by surface mulching.In semi-arid and semi-humid farming areas,the average temperature of MRM was the highest,followed by WRF and SM.3.The ridge and furrow mulching reflected the time and space balance regulation of soil nutrients.The decrease of nutrient content in semi-humid farming area was significantly higher than that in semi-arid farming area.After two consecutive growing seasons,MRM and WRF increased the consumption of organic carbon,total nitrogen and available potassium in the semi-arid farming area during the growing season,which were 0.28 and 0.31 g·kg-1,0.04 and 0.14 g·kg-1,23.48 and 2.96 mg·kg-1higher than CK respectively,while they decreased the consumption of total phosphorus,available phosphorus and alkali-hydrolyzed nitrogen,which were 0.08and 0.10 g·kg-1,0.37 and 0.97 mg·kg-1,1.15 and 2.95 mg·kg-11 lower than CK;MRM and WRF increased the consumption of organic carbon,total phosphorus,available potassium and alkali-hydrolyzed nitrogen in the sub-humid farming area during the growing season,being 1.00 and 0.65 g·kg-1,0.16 and 0.06 g·kg-1,63.74 and 30.61mg·kg-1,8.51 and 5.13 mg·kg-11 higher than CK.4.Ridge and furrow mulching had different effects on soil enzyme activities.Both SM and MRM were beneficial to the increase of soil catalase,sucrase and phosphatase activities,while WRF showed only the increase of phosphatase activity.After two consecutive growing seasons,the activities of catalase and phosphatase in soil of MRM,WRF and SM increased by 0.116,0.013 and 0.052 ml·g-1,0.158,0.115and 0.212 mg·g-11 in semi-arid farming area,respectively,and the soil catalase and phosphatase activities increased by 0.116,0.013 and 0.052 ml·g-1,respectively.Urease activity decreased by 0.200,0.208 and 0.159 mg·g-11 respectively.MRM and SM increased invertase activity by 0.254 and 3.537 mg·g-11 respectively,while WRF decreased invertase activity by 1.753 mg·g-1;The soil sucrase and phosphatase activities of MRM,WRF and SM in semi-humid farming areas increased by 0.591,0.676 and 1.927 mg·g-1,0.302,0.169 and 0.293 ml·g-1,respectively,while the urease activity decreased by 0.211,0.284 and 0.235 mg·g-1,respectively.MRM and SM increased catalase activity by 0.099 and 0.139 ml·g-1,while WRF decreased catalase activity by 0.105 mg·g-1.5.Ridge and furrow mulching also had different effects on the number of different microorganisms in soil.MRM was beneficial to the reproduction of soil bacteria and actinomycetes,while WRF and SM only showed an increase in the number of bacteria,and the increase of soil microorganisms in semi-humid farming area was significantly greater than that in semi-arid farming area.After two consecutive growing seasons,the number of soil bacteria in MRM,WRF and SM in semi-arid farming areas increased by 11.24,35.17 and 30.63 104.g-1,respectively.WRF and SM increased the number of fungi by 5.06 and 4.38 102·g-1,and decreased the number of actinomycetes by 7.50 and 15.67 104·g-1.MRM could increase the number of actinomycetes by 12.83 104·g-11 and decrease the number of fungi by 10.14102·g-1.The number of bacteria and actinomycetes in soil of MRM,WRF and SM in semi-humid farming areas showed an increasing trend,with the increase of bacteria by 34.78,35.73,6.57 105·g-11 and the increase of actinomycetes by 47.52,33.57 and40.91 104·g-1,respectively.MRM increased the number of fungi by 12.87 103·g-1,WRF and SM decreased the number of fungi by 0.62 and 8.42 103·g-1.6.Ridge-furrow mulching could shorten the length of nutritional stage and prolong the span of reproductive period,which was more conducive to the accumulation of spring maize pulp.On the contrary,the vegetative growth stage of maize under straw mulching was significantly prolonged and the reproductive period was shortened.Compared with CK,MRM and WRF in semi-arid farming areas significantly advanced the maize emergence,and increased the emergence rate by13.4%and 19.1%.SM delayed the maize emergence and only increased the emergence rate by 0.34%.MRM and WRF shortened the time from sowing to tasseling,which were 26.5 and 25 days,respectively,and significantly prolonged the reproductive duration by 17 and 16 days,respectively.However,SM prolonged the time from sowing to tasseling by 17.5 days and shortened the duration of reproduction by 11.5 days.MRM and WRF also significantly advanced the maize emergence in semi-humid farming areas,and increased the emergence rate by 1.0%and 2.4%.SM delayed the maize emergence and reduced the emergence rate by 4.4%.MRM and WRF shortened the time from sowing to tasseling by 12 and 9.5 days respectively,but did not significantly prolonged the duration of reproduction.However,SM prolonged the time from sowing to tasseling by 10 days and shortened the duration of reproduction by 3.5 days.7.The ridge-furrow mulching method promoted the establishment of seedlings,increased the vigor and biomass accumulation of seedlings,and optimized reproductive allocation.Compared with CK,MRM and WRF significantly increased the vertical and horizontal growth of maize stalks,increased the ability of leaf area expansion and the leaf area index,and the growth effect of semi-arid farming area was significantly greater than that of semi-humid farming area.The above-ground and under-ground biomass of MRM and WRF increased by 66.96%and 62.79%,19.10%and 45.28%respectively compared with CK in semi-arid farming areas.Meanwhile,MRM and WRF increased the distribution proportion of ear biomass in total aboveground biomass,which was 13.26%and 17.58%higher than CK,while SM increased aboveground biomass by only 8.73%,and under-ground biomass decreased by 21.46%compared with CK,and the distribution ratio of ear biomass in total aboveground biomass was 9.65%higher than CK.The above-ground and under-ground biomass of MRM and WRF increased by 16.41%and 12.66%,12.81%and 27.47%respectively compared with CK in semi-humid farming areas.Meanwhile,MRM and WRF increased the percentage of ear biomass in total aboveground biomass,which was 1.05%and 1.22%higher than CK,while SM decreased by 4.58%and 7.10%compared with CK,and the percentage of ear biomass in total aboveground biomass was 0.22%lower than that of CK.8.Ridge and furrow plastic film mulching optimized the structure of panicle,promoted the success of reproduction and increased the grain output and harvest index.MRM and WRF significantly improved the yield components in semi-arid farming areas.The ear length,ear diameter,grain number per ear,grain weight per plant,100-grain weight,biomass,straw yield and biomass per plant increased by 30.54%and 35.30%,18.88%and 20.96%,59.28%and 65.56%,155.06%and 171.41%,59.93%and 63.72%,66.96%and 62.97%,37.82%and 27.11%,66.96%and 62.97%respectively,compared with CK,while SM increased significantly below the MRM and WRF,followed by 5.96%,4.34%,10.12%,16.88%,5.88%,8.73%,6.04%and8.73%,respectively.In the end,the harvest indices of MRM and WRF were significantly higher than CK by 0.131 and 0.165,while SM was only 0.018 higher than CK.Compared with CK,the above yield components of MRM and WRF in semi-humid farming areas increased by 4.04%and 2.32%,2.03%and 0.25%,3.61%and-2.14%,32.96%and 17.12%,15.51%and 11.44%,16.41%and 12.66%,7.35%and 10.21%,16.41%and 12.66%,respectively,while SM showed the opposite trend,and decreased by 12.27%0.82%,3.91%,11.83%,8.83%,4.58%,0.60%,4.58%compared with CK.Finally,the harvest indices of MRM and WRF increased significantly by 0.051 and 0.014 than CK,while SM decreased significantly by 0.027.9.Ridge and furrow plastic film mulching maintained the high utilization efficiency of resources including water,fertilizer,gas and heat,and significantly increased the grain yield and water use efficiency.The grain yield and water use efficiency of MRM and WRF in semi-arid farming area increased by 155.05%and171.40%,125.44%and 142.80%respectively,while SM only increased by 16.88%and 18.69%compared with CK.The grain yield and water use efficiency of MRM and WRF increased by 32.96%and 17.12%,33.53%and 18.67%respectively in semi-humid farming area,while SM decreased by 11.84%and 9.90%compared with CK.Generally speaking,ridge and furrow mulching improved the water and heat environment of soil,especially the soil moisture storage during fallow period and soil temperature during early growth period,improved the soil quality during the whole growth period,increased the leaf expansion rate significantly,prolonged the period of vegetative growth and reproductive growth in late plant stage,and created good conditions for maize final grain production.Although straw mulching can significantly store soil moisture and improve soil quality,the low temperature effect caused by straw mulching delayed the growth cycle of maize,which was not conducive to the accumulation of dry matter in ears and grains.WRF showed high yield and water use efficiency in semi-arid farming area,while MRM was better in semi-humid farming area.Therefore,WRF is a suitable corn planting technology in semi-arid area of Loess Plateau,and MRM is more suitable in semi-humid farming area. |
