【作者】 毕于运；

【导师】 徐斌；

【作者基本信息】 中国农业科学院 ， 作物生态学， 2010， 博士

【摘要】 中国是世界秸秆大国。秸秆资源的开发利用,既涉及到农业生产系统中的物质高效转化和能量高效循环,成为循环农业和低碳经济的重要实现途径,又涉及到整个农业生态系统中的土壤肥力、环境安全以及可再生资源高效利用等可持续发展问题,还涉及到农民生活系统中的家居温暖和环境清洁,逐步成为农业和农村社会经济可持续发展的必然要求。秸秆资源数量估算主要有三种方法:一是草谷比法;二是副产品比重法;三是收获指数法。本文以大量的农作物种植试验研究文献为主要依据,利用其提供的农作物各部分生物量、收获指数(经济系数)、谷草比等基础数据,结合现实的草谷比实测结果,对我国各类农作物的草谷比进行了仔细的考证,从而建立了更为系统、更为精确的草谷比体系。继而以新建草谷比体系为依据,结合历年农作物生产统计数据,对1952年以来我国历年各类农作物秸秆产量和2008年分省(市、自治区)各类农作物秸秆产量进行了全面系统的估算,并汇总出了1952-2008年全国农作物秸秆总产量和2008年全国各省(市、自治区)秸秆总产量。计算结果表明:(1)2008年全国秸秆产量达到84219.41万t,与1952年(21690.62万t)相比净增2.88倍;(2)中国是世界第一秸秆大国;(3)秸秆是我国陆地植被中年生长量最高的生物质资源,分别相当于全国林地生物质年生长量的1.36倍、牧草地年总产草量的2.56倍和园地生物质年生长量的7.75倍;(4)水稻、小麦、玉米三大粮食作物秸秆产量合计占全国秸秆总产量的2/3左右;(5)全国近一半的秸秆资源分布于全国百分之十几的土地上。在农产品收获过程中,许多农作物需要留茬收割;在农作物生长过程中,尤其是在收获过程中,多数农作物都会有一定量的枝叶脱离其植株而残留在田中;在秸秆运输过程中也会有部分损失,因此并不是所有的秸秆都能够被收集起来。本文通过对各类农作物株高、收割留茬高度、叶部生物量比重、枝叶脱落率、收贮运损失率的调查和资料收集,制定了我国各类农作物秸秆的可收集利用系数,并据此估算了我国各类农作物的可收集利用量。计算结果表明:2008年我国秸秆的可收集利用总量为65102.19万t,平均可收集系数为0.77。秸秆主要有五个方面的用途:一是用作燃料;二是用作饲料;三是用作肥料;四是用作工业原料;五是用作食用菌基料,简称“五料”。本文依据秸秆的形态、质地、密度、物体结构、物质组分、养分含量、热值等自然特征,对其在“五料”利用上的自然适宜性进行了分类评价和综合评价。分类评价结果为,2008年在我国可收集利用的秸秆总量中:(1)最适宜和一般适宜直接燃用的秸秆占1/2以上;(2)适宜和较适宜“三化一电”的秸秆占95%以上;(3)最适宜和适宜沼气生产的秸秆约占90%;(4)适宜和较适宜直接饲喂牛羊的秸秆占近80%,适宜加工饲喂牛羊的秸秆占90%以上,适宜直接饲喂和加工饲喂猪禽的秸秆占1/5以上;(5)适宜工业加工和食用菌种植的秸秆占90%以上。综合评价结果为,2008年在我国可收集利用的秸秆总量中:“草性”和“木性”秸秆各约占1/5,中性秸秆约占3/5。燃用消耗过多,饲用、可再生能源开发利用和工业加工利用偏少是目前我国秸秆利用中存在的突出问题。2008年,在我国秸秆可收集利用总量中,直接燃用量21000万t,占32.26%;新能源开发利用量720万t,占1.11%;饲用量17660万t,占27.13%;工业加工利用量4300万t,占6.61%;食用菌养殖利用量1300万t,占2.00%;直接还田量9200万t,占14.13%;废弃和焚烧量10922万t,占16.78%。目前我国秸秆直接还田量和残留还田量合计为28000多万t,约占全国秸秆资源总产量的1/3,平均每公顷耕地还田秸秆2.33t。根据秸秆资源综合利用与“三农”之内在关系,可将秸秆资源的利用类型划分为三大类:一类是农业生产系统内部的秸秆资源循环利用;二类是农村社会经济系统内部的秸秆资源利用;三类是农村社会经济系统外部的秸秆资源利用。目前,在我国已利用秸秆总量中,一类利用约占52%,二类利用约占39%,三类利用约占9%。我国秸秆开发利用的总体趋势具体体现在“四个增加”、“两个减少”、“一个替代”。“四个增加”:一是秸秆新能源开发利用量增加;二是秸秆饲用量增加;三是秸秆工业加工利用量增加;四是秸秆食用菌种植利用量增加。“两个减少”:一是秸秆废弃和焚烧量减少;二是秸秆直接燃用量减少。“一个替代”是指秸秆过腹还田、秸秆沼肥还田和秸秆过腹沼肥还田逐步替代秸秆直接还田。更多还原

【Abstract】 China is one of the world’s biggest straw producers. In today’s society, the development and utilization of straw resources is closely related to the high-efficient transformation of materials and the high-efficient cycle of energies in the agricultural system, the sustainable development issues like soil fertility, environmental safety and high-efficient utilization of renewable resources in the whole agricultural ecosystem, as well as energy use and environmental cleanness in the daily life of farmers, and as a result, it has gradually become an essential element of the sustainable agriculture , circular agriculture and low-carbon economy.There are three major ways to estimate the quantity of straw resources: the first one is to calculate the ratio of straw to grain; the second one is to calculate the ratio of byproduct; the third one is to calculate the harvest index (HI). Based on a lot of experimental study documents on growing crops, the thesis makes use of the basic data provided in these documents such as biomass of different parts of crops, harvest indexes (economic coefficients) and ratios of straw to grain, takes the measurement results of actual ratios of straw to grain in reality into considerations, conducts thorough textual researches on the ratios of straw to grain of various crops, and sets up a more systematic and more accurate straw-to-grain ratio system. And on the basis of the newly established straw-to-grain ratio system, it refers to the statistics of crops production over the years, makes an all-round and systematic estimation of straw output of different crops in our country over the years since 1952 and straw output of different crops in different provinces in 2008, and then summarizes the gross straw output of whole China from 1952 to 2008 and the gross straw output of different provinces in 2008. The results show: (1) the straw output of the country amounted to 842,194,100 tons in 2008, with a net growth of 288% in comparison with that of 1952(216,906,200 tons); (2) China is the world’s biggest straw producer; (3) Straw is a biomass resource with the biggest annual growth among terrestrial vegetations in our country, respectively 1.36 times the annual growth of forest biomass, 2.56 times the annual gross grass output of grasslands and 7.75 times the annual growth of garden biomass of the country; (4) the total straw output of rice, wheat and corn accounts for about 2/3 of the gross straw output of the country; (5) nearly half of the country’s straw resources are separately located in about 10 percent of the country’s land.During the harvesting of agricultural products, many crops needed to be harvested with stubbles; in the growth process of crops, especially during harvesting, most crops will have a certain amount of branches and leaves falling off their stems and residing in field; there will also be partial loss of straws during transportation. Therefore, not all the straws can be gathered. Through investigations and collections of data on different crops’height, stubble height, ratio of leaf biomass, fall-off rate of branches and leaves and loss rate during collection and storage, the thesis establishes the collectable and usable coefficients of straws of different crops in our country, and on the basis estimates the collectable and usable volumes of straws of different crops of our country. Calculation results show: the gross volume of collectable and usable straws was 65,102,100 tons in 2008, and the average collectable coefficient was 0.77.Straws mainly can be used in five ways: the first one is as fuel; the second one is as feed; the third one is as fertilizer; the fourth one is as industrial raw materials; and the fifth one is as raw materials of edible fungi. Based on the natural features of straws such as shape, quality, density, constituents of matter, nutrient content and heat value, etc., the thesis makes categorized and comprehensive evaluations of the natural suitability for straw use. The results of categorized evaluation on the gross volume of collectable and usable straws in 2008 show that: (1) the straws most suitable and suitable to be used as fuel account for above 1/2 of the total; (2) the straws suitable and sub-suitable for gasification, liquefaction, solidification and power account for 95% of the total; (3) the straws most suitable and suitable for biogas production account for about 90% of the total; (4) the straws suitable and sub-suitable to be directly fed to herbivorous livestock account for nearly 80% of the total; the straws to be processed and then fed to herbivorous livestock account for above 90% of the total, and the straws suitable to be directly fed to or processed and then fed to pigs and poultry account for over 1/5 of the total; and (5) the straws suitable for industrial processing and edible fungi growing account for over 90% of the total. The results of comprehensive evaluation on the gross volume of collectable and usable straws in 2008 straws that: Grass Straw and Wood Straw respectively account for about 1/5 of the total while Neutral Straw accounts for about 3/5 of the total.Excessive consumption of straws as fuel directly and inadequate use of straws as feed, newly renewable energy and industrial material are the prominent problems of straw utilization in our country. Of the gross volume of collectable and usable straws in 2008, 210 million tons of straws were used directly as fuel, accounting for 32.26%; 7.2 million tons were used as newly renewable energy, accounting for 1.11%; 176.6 million tons were used as feed, accounting for 27.13%; 43 million tons were used in industrial processing, accounting for 6.61%; 13 million tons were used to grow edible fungi, accounting for 2.00%; 92 million tons were directly returned to the soil, accounting for 14.13%; and 109.22 million tons were discarded or burned, accounting for 16.78%. At present, the total of straws directly returned to field and residing in soil is over 280 million tons, accounting for 1/3 of the gross output of straw resources, and 2.33 tons of straws are returned to each hectare of farming land on average.According to the internal relations between comprehensive utilization of straw resources and“agriculture, rural areas and farmers”, the utilization type of straw resources can be divided into three groups: the first one is the recycling utilization of straw resources within the agricultural production system; the second one is the utilization of straw resources within the social economic system in rural areas; the third one is the utilization of straw resources outside the social economic system in rural areas. At present, of the gross volume of utilized straws in our country, the first type accounts for approximately 52%; the second type accounts for approximately 39%; and the third type accounts for approximately 9%.The general trend of our country’s exploitation and utilization of straws is specifically embodied by“four increases”,“two decreases”and“one substitute”. The“four increases”refer to increase of use of straws in the new energy development; increase of use of straws as feed; increase of use of straws in industrial processing and utilization; and increase of use of straws in edible fungi planting. The“two decreases”refer to decrease of discarded or burned straws until such practices are completely stopped; and decrease of direct use of straws as fuel.“One substitute”refers to that direct returning of straws to field will be gradually replaced by returning of animal manure and biogas fertilizer from respectively raising domestic animals and biogas production using straws.更多还原