关键词:土地经济学;外来职业农民;Poisson回归;种植多样性 Abstract Crop diversity is an effective strategy for traditional small-peasant to cope with the impact of agricultural risks. The transition of agriculture driven by migrant professional farmers may be different from local peasant households’crop diversity. The purpose of this study aims to investigate the difference of crop diversity between migrant professional farmers and local peasant households and its influencing factors at farm household level. Based on survey data from 393 farmers’crop diversity in Nanjing City, Jiangsu Province in 2015, we established a Poisson regression model. Different from the previous studies, the current investigation was carried out at farmer level, the farmer is not only the household head but also the family member in charge of agricultural production. Furthermore, the crop diversity was valued more directly by crop kinds instead of diversity index. The result shows that several factors affected farm households’ crop diversity. First of all, compared with the local peasant households, the crop diversity of migrant professional farmers is 17% less than that of local peasant households. Moreover, crop acreage has a significant effect on crop diversity, crop diversity decreases approximately 2.7% with an increase of 1 hm2 of crop acreage. Besides, the age of farmers who are in charge of agricultural production, the agriculture land plot quantities of farmers who own, and the distance from peasants residence to the main city zone also have significant effects on crop diversity. Holding all other variables constant, the expected number of crop diversity increases by about 0.9% with an increase of the age of farmers, the expected number of crop diversity increases approximately 4.6% with an increase of 1 plot of agriculture land; the expected number of crop diversity increases approximately 0.8% with an increase of 1 km from peasants residence to the main city zone.
本文的数据主要是通过农户问卷调查方式获得,课题组于2015年11—12月在南京市开展了农户层面土地利用情况的问卷调查。农户调查问卷主要收集了农户基本特征、土地利用情况、农户种植情况、物资投入和收入情况等信息,作物种类设置主要包括水稻、小麦、玉米、薯类和豆类等粮食作物以及蔬菜、瓜果、果树、油料和茶园等经济作物。调查方式如下: (1)首先基于谷歌地图和南京市2010年第六次全国人口普查数据(南京市统计局提供)[33],初步筛选出南京市保有耕地的居委会,以此作为判断该居委会是否有农民的依据。由于鼓楼区和玄武区几乎没有农用地,所以将其排除在外。 (2)在保证9个城区均有居委会被抽取到的基础上,按照分层随机抽样的原则共抽取了15个居委会,并根据各居委会的人口数量比例,将496个样本分配到抽取的各居委会。并且对居委会中的本地农户和外来职业农民分别采取不同的抽样方式: ① 本地农户按分层抽样原则抽取,期间对422户本地农户进行了调查;② 外来职业农民由于数量相对较少,因此采取偶遇和滚雪球抽样,期间对74户外来职业农民进行了调查。调查完成后,对数据加以整理,剔除掉缺漏值和矛盾值,共整理得到有效问卷393份,其中本地农户325份,外来职业农民68份。调查地区样本分布情况见表1。 Table 1 表1 表1调查地区样本分布情况 Table 1Distribution of research area
由表3可知,农户的种植种类存在差异,最多可达8种;农业生产决策者的平均年龄为58岁左右、年轻者不多见,男性居多且受教育程度普遍不高,多为小学毕业;负责农业生产活动的家庭成员多为1~2人(90%左右),最多不超过5人;种植规模多为0.67hm2以下的小规模或0.67~6.67hm2的中小规模,鲜有6.67hm2以上的大规模种植(只有1户种植规模为133.33hm2),农户地块总数存在不同程度的差异,农户所处住地到主城区的平均距离为31.37km左右,所有变量的相关统计情况见表3。 Table 3 表3 表3分析变量的相关统计特征 Table 3Descriptive statistics of variables used in the models
基于本文研究结论,可以看出不同类型农户的种植多样性存在显著差异,农户身份差异导致的种植多样性差异背后的原因是两类农户的农业经济行为差异和农户生计来源的重要性排序差异。农业经济和农业地理研究中根据农民的经济行为差异把农民分为自给农民、半自给农民、半商业农民和商业农民四类,其中商业农民的经济行为与自给农民存在显著差异[35]。作为农业转型升级的重要主体,不同于本地传统农户多样化种植作物,以满足多样化消费需求、获得家庭额外收入来源;外来职业农民的经济行为更趋向于商业农民,更倾向于专业化种植作物,以农业收入为家庭主要收入来源。两类农户种植多样性虽然存在差异,但是其合理发展对区域农业发展具有重要推动作用。辨析不同类型农户的种植多样性差异,理清农户种植多样性的影响因素,能够为合理引导区域农户种植决策和农业转型发展提供参考。 考虑到本文主要是从农户层面这一相对微观尺度上讨论种植多样性的影响因素,因此得到的有关种植多样性影响因素的结论并不能推及区域尺度种植多样性,未来研究还需要进一步考虑在更大尺度的分析。 The authors have declared that no competing interests exist.
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