退耕还林(草)背景下黄土高塬沟壑区长武县粮食潜力及安全分析

Potentiality Analysis of Grain Productivity and Its Security in Changwu County in the Loess Plateau Gully Region against the Background of "Grain for Green" Projection

鉴于黄土高塬沟壑区退耕还林(草)工程和林果业迅速发展所带来的粮食-人口-资源矛盾问题,收集农业气象、耕地等数据,基于GIS技术,采用机制法分析了退耕还林(草)工程实施前后的1993年和2009年黄土高塬沟壑区长武县粮食潜力和安全问题,明确了气候要素限制下长武县各层次粮食生产潜力及开发程度。长武县1993年到2009年可实现粮食潜力总量下降了7.8%,而实际粮食生产总量增产了4.0%,潜力实现率由61.58%增至68.59%。17a间,主要粮食作物播种面积减少了27.8%,单产平均提高44.1%,而人口增长了12.5%,人均播种面积下降了35.9%,人均粮食产量由320.1kg减少至296.0kg,下降了7.5%。温度和土地有效系数的提高是促进可实现粮食潜力增加的主要因素,耕地减少是限制粮食增幅的直接原因,单产提高是促进增产的主要因素。耕地减少、人口增加是该区粮食安全的核心问题,粮食单产的提高是维持该区粮食安全稳定的保障。针对该区粮食安全问题的严峻性,提出必须以全面提高粮食单产为目标,科学增加辅助能量投入,推进基本农田建设,大力推广耕地保育技术和持续高效现代农业。

The issues of grain,population and resources are now becoming increasingly serious in the loess gully area in China,especially under the background of ＂Grain for Green＂ projection from 1999.It is important to evaluate the impacts of ＂Grain for Green＂ projection on the grain productivity and security in the area.In this study,the data of agricultural meteorology in Changwu county in 1993 and 2009 were used to evaluate the grain productivity potentiality.The farmland area and its geographical distribution in 1993 and 2009 were used to check the farmland change and the grain security in the county.The potential productivity for each meterological factor limitation level for main grain plants and the degree of potentiality exploited was calculated using mechanism methodology.Compared with 1993,the achievable potential productivity in 2009 reduced by 7.8%,while the actual grain productivity increased by 4.0%,so the fulfilling rate of the potential natural productivity increased from 61.58% in 1993 to 68.59% in 2009.During the past 17 years,the planting area of main grain plants decreased by 27.8%,grain yield per hectare improved by 44.1%,population increased by 12.5%,the grain planting area per capital decreased 35.9%,the grain yield per capital declined by 7.5% from 320.1 kg to 296.0 kg.The potential productivity was promoted due to the raise of effective coefficient of temperature and land,while the actual grain yield was restricted by the quantity of farmland.Farmland shrinking and population accretion are two core problems in the grain security in the area.So improvement of per capital grain yield is the guarantee for grain security.At the last,the paper was suggested that it be exploited grain potential productivity further and settled down the serious grain security problem in the area,it was requisite to scientifically input assistant energy,to extensively build basic farmland,to conserve cultivated land and popularize the sustainable and efficient modern agriculture technology.