【作者】 蒋端生；

【导师】 曾希柏； 张杨珠；

【作者基本信息】 湖南农业大学 ， 植物营养学， 2008， 博士

【摘要】 南方红壤丘陵区是我国最重要的农业生产基地,该区总面积约占全国土地面积的1/5,人口占全国的40%,耕地占全国的30%,负担了近一半人口的粮食。对该区耕地的质量演化趋势及原因分析的研究具有重要的理论与现实意义。本文对宁乡县第二次土壤普查资料和宁乡县耕地地力调查资料,以及宁乡县水田18a长期施肥定位试验和中国农业科学院祁阳红壤试验站旱地不同母质23a长期施肥定位试验资料的系统分析,探讨了南方红壤丘陵区耕地土壤肥力质量演变规律及其影响因素。所得主要结论如下:1)以湖南省宁乡县为例,研究南方红壤丘陵区耕地土壤肥力质量演变规律及其影响因素。对宁乡县1979年第二次全县土壤普查及2002年耕地地力调查资料进行比较研究与分析。结果表明:南方红壤丘陵区近20a来稻田有机质和氮素含量增幅很明显;土壤有效磷含量成倍剧增;钾素呈亏损之势。研究也表明南方红壤丘陵区旱地肥力变化趋势与稻田相同,但升降幅度不同。土壤酸化严重尤以稻田为甚。在当前施肥水平下,限制水稻产量的主要因素不是土壤养分,而是剖面构型、障碍层位、地形部位和成土母质等土壤与环境条件,建议减少氮肥和磷肥的施用量,增加钾肥的施用量或稻草还田。土壤肥力演变受土壤所处环境条件和土壤内在性质的影响而出现空间变异,制定施肥计划时应当考虑这些因素。2)以湖南省宁乡县稻田长期不同施肥定位试验为例,研究不同施肥对南方红壤区稻田土壤质量的影响。结果表明:施肥是高产的重要保障,施肥处理的早稻产量比不施肥产量高出107%—127%,晚稻施肥处理的产量比不施肥处理高出70%—84%。在各施肥处理中产量以有机肥氮占施肥总氮的30%(即OM30处理)为最高。OM30施肥处理的土壤有机质、全氮、碱解氮和有效磷都得到显著提高,而稻草还田有利于土壤全钾和速效钾的增加。因此,当地农民可以OM30的施肥结构进行施肥,并进行稻草还田,以平衡土壤养分,提高产量和品质,并提高肥料利用率,保障稻田的持续高产稳产优质。3)以中国农科院祁阳红壤试验站为例,利用中国农业科学院祁阳红壤试验站布置的不同母质土壤的旱地长期定位试验,研究不同施肥对南方红壤区不同母质发育的旱地土壤肥力的影响。结果表明:肥力较高、保肥供肥性能好的土壤,作物产量受施肥的影响相对较小,反之则受施肥的影响较大。施肥能提高旱地土壤有机质、全氮和碱解氮含量而有利于植物生长。秸秆还田能起到改进土壤质量的重要作用,尤其有助于改善土壤钾素养分。同一生态气候条件下,以花岗岩红壤对施肥响应最大,第四纪红土红壤居中,紫色土受施肥影响最小。但施肥对花岗岩红壤的增产作用最大,紫色土居中,第四纪红土红壤最小。4)以宁乡县为例,研究了南方红壤丘陵区复杂的土壤和环境条件对土壤生产力的影响。结果表明,水稻土的适宜耕层厚度为15 cm左右,旱耕地适宜耕层厚度应不低于20cm;成土母质对产量的影响以河湖沉积物母质最好,稻田以板页岩母质最差,旱耕地以紫色砂页岩母质最差;水稻以酸性土最好,旱作以中性土最好;研究区稻田有35.2%的存在障碍层,且多为中、高位障碍,是影响水稻产量整体提高的主要因素;水稻和旱作都以壤土为最好,其中,稻作怕砂,旱作怕粘;水稻土适宜的容重为1.00—1.29 g/cm~3。水稻比旱作需要更厚的土层,水稻土有效土层厚度应不低于65cm,旱土应不低于50cm。研究还表明:地貌海拔越高,产量越低;地形通过影响水文条件而影响产量,地势过高,如山坡上部和高岸田,或地势过低的稻田,如丘间洼地,水稻产量都较低;而地势居中的稻田,如高位河漫滩、一级和二级阶地,水稻产量都较高;这可能是基于地形影响水的灌排和土壤物质循环;旱耕地的产量与地形的地势高度成反相关,即山区产量低于丘岗地,丘岗地作物产量低于阶地。地下水位越深,越有利于水稻高产;在实际中,开挖排水沟应将地下水位降至50cm以下为目标;对于耕地,高的灌溉保证率是高产的有力保障;以较强的排涝能力为好。排灌配合,涝时能及时排,旱时能及时灌,是保障水稻高产的基础。5)根据对南方红壤丘陵区稻田和旱土的质量演变规律和机理研究,以及对稻田和旱地的长期定位施肥试验资料的分析研究,归纳总结性地提出了耕地主要保育技术。其中,水田保育技术为:①以无机肥为主,配合有机肥;②应重视农田的田园化建设,并且以灌溉排水体系为核心,降低洼田的地下水位,培育厚度适当的耕层为主要建设内容,是取得水稻高产稳产的基础;③推广稻草秸秆还田,充分利用稻草秸秆的钾素资源;④对于pH低于5.5的水田应适当施用石灰、钙镁磷肥、钢渣磷肥等碱性肥料,降低土壤酸度;⑤成土母质是施肥的重要参考依据。旱地保育技术为:①以有机肥为主,配合无机肥是培肥旱地地力、提高肥料养分利用率、提高作物产量的重要手段;对于砂性土、保肥性弱的土壤,更依赖于施肥;②培育肥沃深厚的耕作层对旱作物生产极为重要,旱地耕作层应大于20cm为宜;③对于pH小于5.0的土壤应适当施用石灰等碱性物质,提高土壤pH,有助于提高产量。更多还原

【Abstract】 Red soil hilly region in southern China is the most important agricultural production base.It is a region with a total area of the national land area of about 1 / 5.Its population accounts for 40%of the country,and the farming occupies 30%of the country.It supplied nearly half of the food needed for all population in China.So there is very important theoretical and practical significance for this arable land’s quality evolution tendency and mechanism’s research.According to the massive research reports and other materials(the materials of the second soil survey of Ningxiang County by myself and soil fertility of arable land survey of Ningxiang,the research and analysis of the location test for the paddy fields in Ningxiang with long-term fertilization for 18 years and the location test for the dry land of different parent materials with iong-term fertilization for 23 years in the Qiyang Red Soil Experiment Station of the Chinese Academy of Agricultural Sciences),I obtain the main conclusion that follows.1) Do the comparative research and analysis by utilizing the materials of the second soil survey of Ningxiang County in 1979 and soil fertility of arable land survey in 2002.The result shows that in the past 20 years,the organic matter and nitrogen content in paddy fields of Ningxiang County has been obviously increasing.The effective phosphorus content in soil doubled.Potassium element showed a trend of loss.The research also indicated that changes in the fertility of dry land have the same trend with the paddy fields,but the fluctuation scope is different.Particularly in the rice fields,the soil acidification became so serious.This findings also indicated that under the current fertilization level,the main factor of restricting rice’s outputs doesn’t rely on soil nutrients but the profile pattern,the obstacles horizon,parts of the terrain and soil parent material and such other descriptive factors,so the experts’ suggestion is that reduce the nitrogen and phosphate fertilizer and increase the potassium fertilizer or back grass fields;The findings also indicated that the evolution of soil fertility influenced by the environmental condition and the inherent nature of soil appears the spatial variation,so these factors should be considered when we make the plan of fertilization.2) Through different long-term tests located in Ningxiang County of Hunan province,the researchers study the impact of different fertilization on the soil quality of paddy field.The findings showed that the fertilization is an important safeguard for high yield.The output of early rice with irrigation is higher up to 107%—127%than that of non-irrigation,meanwhile for late rice with irrigation it is higher up to 70%-84%than that of non-irrigation.During the whole fertilization process,the output which contained the organic fertilizer with nitrogen is the highest, accounting for 30%of the total nitrogen(i.e.the OM30 processing).There is a significant improvement on the soil organic matter,total nitrogen,alkali-hydrolysable nitrogen and the effective phosphorus,which are fertilized by OM30 processing.And the Straw Back Yield can bring the benefit for the increase of soil total K and available K.Therefore,the local farmer can take the OM30 fertilizer procession and carry the Straw Back Yield,in order to balance soil nutrients to enhance the output and quality,and increase the utilization rate of fertilizer to ensure the sustained stable yield and high quality.3) Through the long-term location test for the dry land of different parent materials laid by Qiyang Red Soil Experiment Station of the Chinese Academy of Agricultural Sciences,the research applies on the impact of different fertilization on different parent material.The research indicated that the soil with higher fertility and good nutrient preserving and supplying capability, will get the relatively less impact on crop output from fertilization,on the contrary it will get more. Fertilization is good for the plant growth by increasing the content of organic matter,total nitrogen and alkali-hydrolysable nitrogen,which contain in the soil of dry land.Stalk return to field also can improve the soil quality,especially help to improve soil nutrient K.4) Through investigating the crop output of dry land and paddy fields in Ningxiang County and survey visiting,observing,sampling and determination the soil and environmental factors of the paddy field and the dry land,such as the topography,soil parent material,the underground water level,the irrigation and flood drainage,topsoil and soil thickness,soil texture,soil pH,bulk density,barrier layer and so on,the researchers use the degree of association between crop output and the soil and the environmental conditions to determine the analysis of the size of soil and environmental conditions’ affect on the soil quality.There is no report of this method at home and abroad.The result indicated that suitable thickness of paddy soil is about 15cm,and for dry arable land it should not be lower than 20cm;The alluvial rivers parent material is the best one to influent the output,the rice fields is the worst with the parent material of slate ground,while the dry and plough land is the worst for its purple sand shale parent material;The paddy rice is best with the acid soil,and the dry crop is the best with the neutral soil;The obstacles horizon exist in 35.2%of the rice fields in research region,and many for middle or top digit obstacles.It is also the main factor which influent the whole output increase of rice;Paddy rice and drought-enduring plant take loam soil as best,among of them,the sand is bad for rice raisings,while stick sand harm to drought-enduring plants;The bulk density of paddy rice is suitable for 1.00-1.29g/cm~3; Compared to drought-enduring plants,paddy rice needs thicker soil layer.The effective thickness of the layer for rice land should not be less than 65 centimeters,and for dry it should not be less than 50 centimeters.The research also showed that the altitude is higher,and the output is lower; The terrain affects the output through hydrological conditions,for example,higher terrain will get lower production in these places such as the upper slopes and fields with high bank or low-lying paddy fields,and low-lying land between the mound;However,the paddy fields placed in the middle of terrain,such as the high floodplain and the first and second terrace,will get higher production.This may be due to topographic impact on the irrigation & drainage and also the soil material cycle.The output of diy arable land and topographical height are anti-related for each other.It means that the output in mountainous area is higher than that of hilly and gang land,while the latter’s production is lower than that in the terrace.The deeper water table is beneficial to the rice’s production.In fact,we should aim at descending the water level to 50 centimeters below when digging the drainage channel.Regarding the arable land,the high guaranteed rate for irrigation is the powerful safeguard for the high yield,and also it is better with a strong capacity of drainage.Ensuring high-yield rice based on cooperating the irrigation and drainage together,and making sure that both of them can be scheduled in a timely manner.5) Utilizing the materials of the second soil survey of Ningxiang County and soil fertility,as well as the findings of long-term location tests of fertilization on the paddy fields of Ningxiang and dry land of Qiyang,the researchers proposed the major land conservation techniques in summary and induction.The technologies of the conservation for paddy fields are following: First,dealing with inorganic-based fertilizer,and combining the organic one.Second,we should focus on the idyllic construction of farmland.Also we should take the system of irritation to the core,and put construction mainly on pushing the high & filling the low land,lowering the groundwater level of depression field and cultivating the appropriate thickness of topsoil.That is the basis of reaching a high and stable field.Third,promoting to return stalk and straw to field, and make full use of the K resources of stalk and straw.Fourth,the paddy fields whose PH lower than 5.5 should be applied for the alkaline fertilizer in proper way such as lime,fused calcium and magnesium phosphate and steel slag with phosphate fertilizer.That will reduce soil acidity.Finally, the parent material is an important reference for fertilization.The technologies of the conservation for dry land are following:First,the important measure to rich the fertility of dry land and increase the output is to take the organic manure mainly and also combing the inorganic fertilizer.Second, cultivating the fertile and deep plow layer is great important to the producing of dry crops.The thickness of plow layer in dry land should be bigger than 20 centimeters.Third,the soil pH less than 5.0 should employ alkaline matters such as lime and so on.From this,the soil pH will get higher and it will help to raise the output.更多还原