【作者】 杨莹莹；

【导师】 黄丽；

【作者基本信息】 华中农业大学 ， 土壤学， 2010， 硕士

【摘要】 本研究以湖北省咸宁市侵蚀红壤为供试对象,大田试验设置了作物对照(CK)、作物+聚丙烯乙酰(PAM) (C1)、作物+稻草覆盖(C2)、作物+带状牧草(C3)、作物+PAM+带状牧草(C4)和作物+稻草覆盖+带状牧草(C5)等6个处理,分别于种植花生前(A)、花生收获后(B)和小麦收获后(C)采集表层土壤样品,并结合室内土培试验,分析了不同修复措施下土壤肥力、团聚体组成及其稳定性的变化,研究了水稳性团聚体中有机质的分布规律,探讨了不同措施提高红壤肥力、改善土壤结构的机理,以期为侵蚀红壤结构退化的修复重建提供理论依据。研究结果表明：1.大田试验中,B时期各处理(除C2)的pH值和阳离子交换量(CEC)均高于CK,说明修复后土壤的缓冲性能增强,相对于CK减缓了土壤pH值的下降；B时期各处理土壤的全氮、全磷含量的平均值分别比A时期提高了50%、56%。大田小区不同时期土壤有机质含量的变化趋势为B>C>A,C时期C2处理的有机质含量比CK增加了20.63%,其他处理间无显著差异；室内土培试验表明,稻草3.2 gkg-1。(D1)处理的土壤有机质含量比对照(CK)上升了33.06%,其他处理间无显著差异。大田试验不同时期土壤碱解氮含量表现为C>B>A,土壤速效磷和速效钾含量均表现为B>C>A,B、C时期均以C4处理的碱解氮含量最高,C时期C2和C5处理土壤速效钾分别比CK提高了152.67%、59.25%；土培试验表明,PAM有利于土壤碱解氮含量的提高,稻草可增加土壤速效磷、速效钾含量,土壤速效钾含量随着稻草施用量的增加而显著上升。随着修复时间的延长,大田小区土壤游离态铁铝氧化物含量逐渐减少,非晶形铁铝氧化物含量逐渐增加,说明土壤晶形铁铝氧化物逐渐向非晶形转化,铁铝氧化物的活化度逐渐提高。2.各处理干筛团聚体以大粒径(>4 mm,4-2 mm)为主,稻草和PAM可显著增加土壤>4 mm干筛团聚体的含量。湿筛后,各处理土壤团聚体的组成发生变化。大田实验中,各级水稳性团聚体含量从高到低的顺序是：<0.25 mm、1-0.5 mm、0.5-0.25 mm、2-1 mm、4-2 mm、>4 mm,随着修复时间的延长,<0.25 mm的微团聚体逐渐向2-1 mm和0.5-0.25 mm的大团聚体转变,C时期各处理>0.25 mm的水稳性团聚体含量比CK增加了23.57%-40.23%；土培试验中,PAM可显著提高>4 mm水稳性团聚体的含量,且随着PAM用量的增加而增加。用>0.25 mm水稳性团聚体含量(WSA)、>0.25 mm团聚体的破坏率(PAD)和平均重量直径(MWD)来衡量土壤团聚体稳定性,结果表明,大田试验以C2、C4处理的团聚体稳定性较高,土培实验中PAM2 g kg-1(P1)、稻草1.6 g kg-1+PAM1 g kg-1 (D2P2)、稻草3.2 g kg-1+PAM1 g kg-1 (D1P2)处理的团聚体稳定性显著高于其他处理。3.大田试验不同时期水稳性团聚体的有机质含量表现为B>C>A。随着团聚体粒径(>4 mm,4-2 mm,2-1 mm,1-0.5 mm,0.5-0.25 mm)的减小,水稳性团聚体的有机质含量逐渐降低。B、C时期团聚体有机质含量分别以C4、C5处理的团聚体有机质含量最高。土壤有机质含量与各粒径水稳性团聚体的有机质含量呈线性正相关,与小粒径(2-1 mm,1-0.5 mm,0.5-0.25 mm)团聚体有机质含量的相关性达极显著水平,相关系数为0.7792-0.8286。同一粒径(除0.5-0.25 mm)下,C2处理水稳性团聚体有机质含量与土壤有机质含量的相关系数(0.9338-0.9962)明显高于其他处理的。4.大田试验中,无论是4-5 mm的干筛团聚体还是水稳性团聚体,团聚体有机质含量表现为内层>外层,B时期团聚体内外层有机质含量高于C时期,各处理干筛团聚体外层有机质含量低于土壤有机质含量,内层有机质含量与其相差不大,而水稳性团聚体内外层有机质含量均明显高于土壤有机质含量。5.从提高侵蚀红壤肥力和团聚体稳定性方面来看,本研究认为大田试验中C2和C4处理的修复效果好于其他处理。更多还原

【Abstract】 In this research, taking eroded red soil of Xianning City, Hubei Province as experimental material, six treatments control (CK), PAM (C1), straw mulch (C2), contour hedgerow (C3), PAM+contour hedgerow (C4) and straw mulch+contour hedgerow (C5) were set in field test, and samples of topsoil were collected before planting peanut (A) and after harvesting of peanut (B) and wheat (C) respectively. Combining with soil incubation experiment, the changes of soil fertility, aggregates distribution and stability of different restoration measures were studied, as well as the distribution of organic matter (OM) in water stable aggregates of various sizes, aggregate interiors and exteriors. It was expected to study the effects of different measures on improving red soil fertility and soil structure in order to provide theoretical basis for the reconstruction of eroded red with degradated structure. The results showed that:1. In field test, both pH and cation exchange capacity (CEC) in all treatments (except C2) were higher than those of CK in B period, indicating that soil buffer capacity was strengthened and soil pH of all treatments decreased slowly relative to CK. Compared with A period, the content of total nitrogen and total phosphorus in B period were increased by 50%,56% respectively.The order of soil OM content in different periods of field test was B>C>A, and OM content of C2 treatment increased significantly by 20.63% in contrast to CK during C period, but there was no significant difference between other treatments. In soil incubation experiment, OM content of the treatment with 3.2 g kg-1 straw mulch (D1) significantly grew up to 8.13 g kg-1 compared with control (CK), while no significant differences were observed between other treatments.The content of soil available nitrogen in field test increased gradually from A period to C period, while the order of available phosphorus and available potassium were B>C>A. C4 treatment had the highest percentage of soil available nitrogen in either B period or C period. Besides, available potassium content of C2 and C5 treatment in C stage were significantly higher than that of CK, and its increasing extent reached 152.67%, 59.25% respectively. In soil incubation experiment, it was found that PAM enabled to improve soil available nitrogen content, while rice straw was beneficial to increasing the content of available phosphorus and available potassium, especially available potassium rose significantly with the increasing of rice straw amount.With restoration time prolonged, free iron-aluminum oxides content was gradually decreased, but the amorphous showed opposite trend, it reflected that iron-aluminum oxides gradually transformed from crystalline to amorphous with the improvement of activation grade.2. In both field test and soil incubation experiment, not only dry aggregates in all treatments were mainly distributed in>4 mm,4-2 mm, but also rice straw and PAM could significantly increase the content of>4 mm dry aggregate. After wet sieving, from high to low, the content of water stable aggregates percentage of field test were<0.25 mm,1-0.5 mm,0.5-0.25 mm,2-1 mm,4-2 mm,>4 mm. Micro-aggregates (<0.25 mm) were agglomerated to 2-1 mm and 0.5-0.25 mm, and the content of water stable aggregates (>0.25 mm) in all treatments were higher than that of CK in C period, with the increasing extent from 23.57% to 40.23%. Meanwhile, the percentage of>4 mm water stable aggregates were greatly improved with the increasing quantity of PAM.Aggregate stability were studied through three aspects which were>0.25 mm water stable aggregates (WSA),>0.25 mm percentage of aggregate disruption (PAD) and mean weigh diameter (MWD), the aggregate of C2 and C4 treatments were more stable in field test, while PAM2 g kg-1 (P1), straw mulch 1.6 g kg-1+PAM1 g kg-1 (D2P2), straw mulch 3.2 g kg-1+PAM1 g kg-1 (D1P2) were relatively stable in soil incubation experiment.3. In field test, the order of organic matter content of water stable aggregates in different periods was B>C>A, and the content were reduced with the diminishing of aggregate diameter. Water stable aggregates of C4 and C5 hit the highest organic matter percentage in B and C stage. Moreover, there was a linear positive correlation happened to organic matter between soil and water stable aggregates, and the correlation coefficients (r) of small aggregates (2-1 mm,1-0.5 mm,0.5-0.25 mm) ranged from 0.7792 to 0.8286, with a very significant level. The correlation coefficients of C2 treatment (0.9338-0.9962) were obviously higher than that of other treatments.4. Both in 4-5 mm dry aggregate and in water stable aggregate of field test, organic matter in aggregate exteriors was lower than that in interiors. Organic matter content of aggregate interiors in B period was over that in C period. Compared with soil organic matter, organic matter content of dry aggregate exteriors was lower, but slight difference for interiors. However, soil organic matter was much lower than that of water stable aggregate interiors and exteriors.5. With respect to improving fertility and aggregate stability of eroded red soil, C2 and C4 treatments had better restoration effect in field test.更多还原