不同树龄坡地果园土壤养分和水质特征

Characteristics of soil nutrients and water quality in slope orchards with different tree ages

赣南红壤丘陵区坡地果园生态与环境效应随果园种植年份的变化机制尚不清晰,针对此问题,开展不同树龄坡地果园土壤养分和水质特征研究。以南方红壤丘陵区5个不同树龄坡地果园为研究对象,实地采样和室内分析测试相结合,利用统计软件(SPSS 22.0)对不同树龄果园坡地土壤总氮(TN_(s))、总磷(TP_(s))、总钾(TK_(s))、有机质(SOM)和果园塘坝水体总氮(TN_(w))、总磷(TP_(w))、氨氮(NH 3-N)、化学需氧量(COD_(cr))差异性进行相关性分析。结果表明土壤肥力指数分值(SS fi)随果园种植年份呈先下降后升高的趋势,短期(6年)内果园土壤养分无显著性差异,SS fi在3年果园最低为48分至15年果园最高为74分。果园种植大于9年后TN_(s),TP_(s)及SOM急剧上升,15年坡地果园TN_(s),TP_(s),SOM分别达到0年果园的2.2倍、3.0倍和3.5倍。SOM与TP_(s)、TN_(s)呈极显著正相关关系,坡地果园土壤有机物质输入与土壤氮磷含量呈显著线性相关。不同树龄果园塘坝水体水质变化差异性低于土壤养分,仅NH 3-N呈显著性差异,随果园种植年份呈先增加后降低趋势。15年果园水体水质指标(TN_(w)外)与0年果园基本一致。果园塘坝水体水质指数分值(SW_(qi))随果园种植年份呈波动趋势(69~78分),TN_(w)与COD_(cr)分值较低,分别为果园塘坝水体主、次要污染物。建议应增强幼龄果园水保措施的固氮能力并提升土壤有机质,同时控制塘坝水体总氮和有机质的输入,从而提高坡地果园生态效益的时效性。

The changing effects of slope orchards on ecology and environment with the increase of planting years in red soil hilly region of southern Jiangxi Province are still unclear.Thus,the differences of soil nutrients and water quality among slope orchards with different tree ages are analyzed.Five slope orchards with different tree ages are selected in hilly red soil region of southern Jiangxi Province as the study area.Soil and water samples are collected in the field and taken into the laboratory for analysis.The statistical software(SPSS 22.0)is used to identify the differences among different kinds of soil nutrients and water quality indexes,including soil total nitrogen(TN_(s)),soil total phosphorus(TP_(s)),soil total potassium(TK_(s)),soil organic matter(SOM)and total nitrogen in pond water(TN_(w)),total phosphorus in pond water(TP_(w)),ammonia in pond water(NH 3-N),and chemical oxygen demand in pond water(COD_(cr)).The correlations of these nutrients are also analyzed.The results show that the score of soil fertility index(SS fi)first decreases and then increases with the increase of planting years.In the short term(less than 6 years),there is no significant difference among soil nutrients in slope orchards with different tree ages.SS fi reached the lowest score of 48 points in 3-year-old orchard and showed the highest score of 74 points in 15-year-old orchard.TN_(s),TP_(s)and SOM increased sharply after planting more than 9 years.TN_(s),TP_(s)and SOM in 15-year-old orchard reached 2.2,3.0 and 3.5 times of 0-year-old orchard,respectively.SOM is positively correlated with TN_(s)and TP_(s).The input of soil organic matter is closely related to the sources of soil nitrogen and phosphorus in slope orchards.The variations of water quality in pond water were not as significant as those among soil nutrients in slope orchards with different tree years.It showed that only NH 3-N had significant differences among slope orchards with different tree ages,which first increased and then decreased with the increase of planting year.Water quality indexes(except TN_(w))in pond water of 15-year-old orchard were the same as those of 0-year-old orchard.The score of water quality index(SW_(qi))in pond water showed a fluctuation trend with the increase of planting year,ranging at scores of 69-78 points.TN_(w)and COD_(cr)were the main pollutants in pond water,displaying low scores.Overall,the nitrogen fixation capacity of soil and water conservation measures should be highly strengthened to improve the soil organic matter in the yonger slope orchards.The input of total nitrogen and organic matter in pond water should be under control to improve the ecological benefits of the slope orchards with the increase of planting years.