山地丘陵区耕地质量可提升潜力空间分布及保护分区——以重庆市江津区为例

基于地貌尺度划定耕地保护区可为山地丘陵地区国土空间规划编制提供新的视角。本研究采用耕地质量提升潜力模型和空间自相关分析方法,探讨重庆市江津区耕地质量可提升潜力空间分布特征;在与耕地质量可改良因子限制程度相结合的基础上,根据耕地保护分区识别与强度诊断模型,划定不同地貌类型的耕地保护区。结果表明:研究区耕地质量可改良因子限制程度总体呈“南北高中间低”的带状分布形态;高限制区所占面积最大,占比34.78%。研究区耕地自然等可提升潜力指数呈现东南向西北降低的分布趋势“,随机”型分布较多,占比41.71%;耕地利用等可提升潜力指数呈“北高南低”的分布趋势“,高-高”型“、低-低”型和“随机”型三者分布占比相当。浅丘平坝区应以重点保护为主,将其划为永久基本农田保护范围;中丘区应将一般保护与重点保护相结合,尽力避免非农建设的挤占;高丘区和山地区应将一般保护与限制保护相结合,通过退耕还林还草、农业结构调整促进生态农业建设。将耕地质量提升潜力与耕地质量限制程度相耦合能够更加明确耕地近期重点保护的区域,同时从地貌尺度划定耕地保护区能够与耕地差异化保护的现实需求相适应,两者可为山地丘陵区耕地资源保护与可持续利用提供理论支撑。

基于“三生”视角的山地丘陵区土地整治功能分区——以重庆市綦江区为例

采用"三生"功能指数测算和系统聚类分析相结合的方法,以重庆市綦江区为例,进行土地整治分区研究。结果表明:(1)各街镇地形差异较大,其"三生"功能指数随立地条件的不同呈现出明显的空间分异性。生产功能指数与立地条件指数在0.05水平上呈显著正相关(r=0.522),生活功能指数与立地条件指数在0.01水平上呈显著正相关(r=0.595),生态条件指数与立地条件指数相关性不显著,相关系数为负(r=-0.134)。(2)结合聚类结果和实际情况,将研究区分为4个土地整治区,并提出相应的整治措施。

基于地形复杂度的重庆市耕地“宜机化”改造适宜性评价

"宜机化"改造是推进丘陵山地农业机械化发展的根本之路,对其进行科学的适宜性评价能合理规划改造进程,对提高丘陵山地"宜机化"改造的效率和准度具有重要意义。本文选取高程、坡度和地块破碎度等3个地形限制因素,以重庆市各区县为评价单元,结合GIS空间分析功能及数据包络法(DEA),对耕地进行"宜机化"改造适宜性评价。结果表明:1)重庆市耕地小而碎,主要分布在中部和西部。2)耕地主要分布在坡度为6°~15°、海拔高度为200~500 m区域,其中海拔在300~400 m范围内的耕地是"宜机化"改造最理想的区域,占主要耕地的48.88%。3)通过自然间断点分级法(Jenks)将综合地形复杂度指数分段后得到6个适宜程度:非常适宜、适宜、比较适宜、比较不适宜、不适宜和非常不适宜;低于平均地形复杂度指数值的区县共25个,包括处于非常适宜区的潼南区等9个区县、处于适宜区的璧山区等7个区县和处于比较适宜区的綦江区等9个区县。评价结果与重庆市地貌格局高度重合,建议优先考虑在适宜性程度高的区县进行"宜机化"改造。因此,在GIS空间分析功能的支撑下,基于地形复杂度的适宜性评价方法能有效评价丘陵山地耕地"宜机化"改造的适宜性,对耕地坡度<15°的区域进行"宜机化"改造将大大提升重庆市农业机械化程度,重庆市耕地"宜机化"改造潜力大。

紫色页岩发育土壤的颗粒特性及其对抗剪强度的作用机制

土体发生破坏最开始往往是从内部的土壤颗粒破坏开始,而抗剪强度是反映土体抵抗剪切破坏能力的重要指标。本文以紫色页岩发育的坡耕地土壤为研究对象,通过测定土样颗粒组成以及不同含水率和垂向压力下的抗剪强度,研究页岩发育的土壤颗粒特性及其对抗剪强度的作用机制。结果表明从坡顶至坡脚,土壤颗粒组成与其母岩颗粒组成具有显著相关性;土壤中<0.25 mm颗粒累计含量在995.65～998.62 g/kg之间,其中以0.25～2 mm岩石碎屑存在的土壤颗粒含量为439.80～510.40 g/kg,以0.25～2 mm团聚体存在的土壤颗粒含量为6.01～80.50 g/kg,随着位置高程的降低,土壤中岩石碎屑和团聚体的含量并没有显著变化。在含水率从7%增加到25%的过程中,土壤水分与内摩擦角呈负相关关系且对内摩擦角的影响随着高程的降低缓慢减小,而对黏聚力的影响是随着含水率的增加单一坡位黏聚力呈现先增加后减少的趋势,但是随高程降低变化并不明显。因此,在紫色页岩发育的土壤颗粒组成中存在大量<2 mm的岩石碎屑,这些大量致密坚硬的岩石碎屑提高土壤抗剪强度同时减弱了抗剪强度的水敏性。

Temporal variation of soil water and its influencing factors in hilly area of Chongqing,China

The paper studied the temporal variation of soil water content and its influencing factors in hilly area of Chongqing by the yearly data of 2006 and 2007.According to precipitation anomaly percentage,the year 2006 was a dry year and 2007 a normal year.In the dry year 2006,the variations of soil moisture in all three layers(0-10 cm,10-20 cm,20-40 cm)were medium(10%<CV<30%);in the normal year 2007,the variation in the layer of 0-10 cm was strong(CV>30%),and those of the two deeper layers were weak(CV<10%).Hence,the seasonal variation of soil moisture in the humid area was large in the dry year and small in the wet year.The probability distributions of soil moisture in all three layers in both dry and normal years showed single-peak shapes.However,peak locations and values varied with different layers and years.Among factors affecting the temporal variation of soil moisture in the 0-10 cm layer,during March to May,the meteorological factors including temperature,sunshine and precipitation were all inversely correlated with soil water content variation.The correlations with average temperature and accumulated temperature were both highly significant P<0.01(P=0.00).The inverse correlations with sunshine and precipitation were significant P<0.05(P=0.01).Among soil physical properties,except for bulk density which was inversely correlated with soil moisture,all other properties were positively correlated.Organic material was positively correlated with soil moisture,which suggested that organics had the sponge effect and contributed to soil water storage and movement.During the period of June to September,there was no significant correlation between soil water content and total storage.The meteorological factors of temperature,accumulated temperature and sunshine were all inversely and highly significantly correlated with soil water content P<0.01(P=0.00).

Restoration technologies of damaged paddy in hilly post-mining and subsidence-stable area of Southwest China

The paddy fields and water storage facilities are seriously damaged by the coal mine subsiding in the hilly post-mining and subsidence-stable areas in China,which make the farmers there being suffered greatly from the lack of water for traditional rice cultivation and daily life.The purpose of this paper is to find a method to restore the damaged paddy fields,thereby promoting sustainable development of land resources,and alleviating the contradiction between people and land,as well as creating a more inhabitable environment.The research methodology included field experiments,cultivated observation,and field investigation.This paper selected the Songzao Mining Area as the research area,and focused on the restoration technologies of damaged paddy fields,through the following four different measures at three experimental fields:(1)Traditional repeated cattle plowing(CK);(2)Water retention agent with repeated cattle plowing(W&C);(3)Film without holes under tilth depth(FO);and(4)Film with holes under tilth depth(FW).At last,a contrastive analysis of the four measures was made according to the results of the experiments.The results show that the use of water retaining agent with repeated cattle plowing(W&C)can be the most appropriate method to restore the damaged paddy field in the hilly post-mining and subsidence-stable area in southwest China.Compared with the other three measures,its water productivity is the maximum(0.81 kg/m3),and the net income is the highest(1403$/hm^(2)).What’s more,it is simple,short time-consuming,and low cost,which is benefit to generalize the use of this restoration technology.