利用方式和土壤肥力对土壤团聚体和养分的影响

The size distribution of water-stable aggregates and the variability of organic C, N and P contents over aggregate size fractions were studied for orchard, upland, paddy, and grassland soils with high, medium, and low fertility levels. The results showed that > 5 mm aggregates in the cultivated upland and paddy soils were 44.0% and 32.0%, respectively, less than those in the un-tilled orchard soil. Organic C and soil N in different size aggregate fractions in orchard soil with high fertility were significantly higher than those of other land uses. However, the contents of soil P in different size aggregates were significantly greater in the paddy soil as compared to the other land uses. Soil organic C, N and P contents were higher in larger aggregates than those in smaller ones. The amount of water-stable aggregates was positively correlated to their contribution to soil organic C, N and P. For orchard and grassland soils, the > 5 mm aggregates made the greatest contribution to soil nutrients, while for upland soil, the 0.25-0.053 mm aggregates contributed the most to soil nutrients. Therefore, the land use with minimum disturbance was beneficial for the formation of a better soil structure. The dominant soil aggregates in different land use types determined the distribution of soil nutrients. Utilization efficiency of soil P could be improved by converting other land uses to the paddy soil.     

中国黄土高原区轮耕对土壤团聚体、有机碳氮含量的影响

In rain-fed semi-arid agroecosystems, continuous conventional tillage can cause serious problems in soil quality and crop production, whereas rotational tillage (no-tillage and subsoiling) could decrease soil bulk density, and increase soil aggregates and organic carbon in the 0-40 cm soil layer. A 3-year field study was conducted to determine the effect of tillage practices on soil organic carbon (SOC), total nitrogen (TN), water-stable aggregate size distribution and aggregate C and N sequestration from 0 to 40 cm soil in semi-arid areas of southern Ningxia. Three tillage treatments were tested: no-tillage in year 1, subsoiling in year 2, and no-tillage in year 3 (NT-ST-NT); subsoiling in year 1, no-tillage in year 2, and subsoiling in year 3 (ST-NT-ST); and conventional tillage over years 1-3 (CT). Mean values of soil bulk density in 0-40 cm under NT-ST-NT and ST-NT-ST were significantly decreased by 3.3% and 6.5%, respectively, compared with CT, while soil total porosity was greatly improved. Rotational tillage increased SOC, TN, and water-stable aggregates in the 0-40 cm soil, with the greatest effect under ST-NT-ST. In 0-20 and 20-40 cm soils, the tillage effect was confined to the 2-0.25 mm size fraction of soil aggregates, and rotational tillage treatments obtained significantly higher SOC and TN contents than conventional tillage. No significant differences were detected in SOC and TN contents in the >2 mm and <0.25 mm aggregates among all treatments. In conclusion, rotational tillage practices could significantly increase SOC and TN levels, due to a fundamental change in soil structure, and maintain agroecosystem sustainability in the Loess Plateau area of China.     

长期施肥和耕作管理对华北平原土壤肥力的影响

In the North China Plain, fertilizer management and tillage practices have been changing rapidly during the last three decades; however, the influences of long-term fertilizer applications and tillage systems on fertility of salt-affected soils have not been well understood under a winter wheat (Triticum aestivum L.)-maize (Zea mays L.) annual double cropping system. A field experiment was established in 1985 on a Cambosol at the Quzhou Experimental Station, China Agricultural University, to investigate the responses of soil fertility to fertilizer and tillage practices. The experiment was established as an orthogonal design with nine treatments of different tillage methods and/or fertilizer applications. In October 2001, composite soil samples were collected from the 0–20 and 20–40 cm layers and analyzed for soil fertility indices. The results showed that after 17 years of nitrogen (N) and phosphorous (P) fertilizer and straw applications, soil organic matter (SOM) in the top layer was increased significantly from 7.00 to 9.30–13.14 g kg-1 in the 0–20 cm layer and from 4.00 to 5.48–7.75 g kg-1 in the 20–40 cm layer. Soil total N (TN) was increased significantly from 0.37 and 0.22 to 0.79–1.11 and 0.61–0.73 g N kg-1 in the 0–20 and 20–40 cm layers, respectively, with N fertilizer application; however, there was no apparent effect of straw application on TN content. The amounts of soil total P (TP) and rapidly available P (RP) were increased significantly from 0.60 to 0.67–1.31 g kg-1 in the 0–20 cm layer and from 0.52 to 0.60–0.73 g kg-1 in the 20–40 cm layer with P fertilizer application, but were decreased with combined N and P fertilizer applications. The applications of N and P fertilizers significantly increased the crop yields, but decreased the rapidly available potassium (RK) in the soil. Straw return could only meet part of the crop potassium requirements. Our results also suggested that though some soil fertility parameters were maintained or enhanced under the long-term fertilizer and straw applications, careful soil quality monitoring was necessary as other nutrients could be depleted. Spreading straw on soil surface before tillage and leaving straw at soil surface without tillage were two advantageous practices to increase SOM accumulation in the surface layer. Plowing the soil broke aggregates and increased aeration of the soil, which led to enhanced organic matter mineralization.     

采用土壤质量指数评估施肥对集约型稻麦轮作系统中土壤物理性质的影响

Soil quality assessment has been suggested as an effective tool for evaluating sustainability of soil and crop management practices.The objective of this study was to develop a sensitive soil quality index(SQI) based on bulk density(BD),water-holding capacity(WHC),water-stable aggregates(WSA),aggregate mean weight diameter(AMWD),total organic C(TOC) and C input to evaluate the important rice-wheat cropping system on an Inceptisol in India.A long-term experiment has been conducted for 18 years at the Indian Council of Agricultural Research-Indian Institute of Farming Systems Research,Modipuram,India.The treatments selected for this study were comprised of a no-fertilizer control and N,P and K fertilizers(NPK) combined with Zn and S fertilizers(NPK+ Zn+S),farmyard manure(NPK+FYM),green gram residues(NPK+GR) and cereal residues(NPK+CR),laid out in a randomized complete block design with three replications.Soil samples were collected and analyzed for BD,WHC,WSA and TOC.Correlation analysis revealed that both rice and wheat yields signi?cantly increased with the increases in AMWD,TOC and C input,but decreased with the increase in BD.The SQI values were then generated based on regression analysis of BD,WSA,AMWD,TOC and C input with rice and wheat yields for the 0–15 and 15–30 cm soil layers,respectively.Regression analyses between crop yields and SQI values showed a quadratic type of relation with the coeffcient of determination(R~2) varying from 0.78 to 0.89.With regard to soil sustainability,applying crop residues to both rice and wheat could maintain soil quality for a longer period,whereas the highest yields of both the crops were recorded in the NPK+Zn+S treatment.The regression equations developed in this study could be used to monitor soil quality in a subhumid tropical rice-wheat cropping system.     

长期日光温室试验条件下不同施肥处理对土壤团聚体稳定性和铁铝氧化物含量的影响

Soil in greenhouses is likely to suffer a gradual decline in aggregate stability. Determination of the effects of different fertiliser practices on soil aggregate stability is important for taking advantage of solar greenhouses. Soil aggregate stability and iron(Fe) and aluminium(Al) oxide contents were investigated in a 26-year long-term fertilisation experiment in greenhouse in Shenyang, China,under eight fertiliser treatments: manure(M), fertiliser N(FN), fertiliser N with manure(MN), fertiliser P(FP), fertiliser P with manure(MP), fertiliser NP(FNP), fertiliser NP with manure(MNP), and control without any fertiliser(CK). A wet sieving method was used to determine aggregate size distribution and water-stable aggregates(WSA), mean weight diameter and geometric mean diameter as the indices of soil aggregate stability. Different fertiliser treatments had a statistically significant influence on aggregate stability and Fe and Al oxide contents. Long-term application of inorganic fertilisers had no obvious effects on the mass proportion of aggregates. By contrast, manure application significantly increased the mass proportion of macroaggregates at the expense of microaggregates. All treatments, with the exception of FNP, significantly increased the stability of macroaggregates but decreased that of microaggregates when compared with CK. Aggregation under MP and MN was better than that under M and MNP; however,no significant differences were found among inorganic fertiliser treatments(i.e., FN, FP, and FNP). A positive relation was found between pyrophosphate-extractable Fe and WSA(r = 0.269), but no significant relations were observed between other Fe and Al oxides and aggregate stability.     

稻草还田的土壤肥力与产量效应研究

18年稻草还田定位试验和3年田间示范试验研究表明,稻草直接还田对改善土壤理化性状具有显著效果.长期定位试验化肥 稻草还田区水稻产量相对无肥区(CK)增产80.8%,但与等量NPK的纯化肥区差异不显著.示范试验结果表明,短期稻草还田具有显著增产作用,增产率达3.7%～6.8%.氮肥的增产作用显著,建议氮肥和习惯氮肥处理增产率分别为38.8%和47.4%,而氮肥的农学产量效益分别为每公斤纯氮增产谷粒13.7 kg和11.7 kg,肥料报酬率随施氮量增加而递减.经济效应分析表明,稻草还田配施减量氮肥可降低肥料成本,提高经济效益.     

三峡库区坡改梯地不同土地利用方式的土壤肥力质量评价研究——以重庆市巫山县为例

以重庆巫山县典型坡改梯地为例,选取5种不同土地利用方式对土壤肥力质量进行评价,结果表明:研究区的土壤肥力整体处于中下等水平,5种地类按土壤肥力大小排序为荒地(0.501)>林地(0.431)>菜地(0.427)>园地(0.390)>粮田(0.349),农耕用地的土壤肥力明显低于林地和荒地,可见退耕还林还草具有明显的土壤培肥作用,人类活动和土地利用方式对土壤质量有很大影响,合理规划土地利用方式对土壤质量提高有重要作用。     

中国三峡库区坡地果园保护性措施减少氮磷的流失

The increased application of chemical fertilizers in citrus orchards and the non-point source nitrogen (N) and phosphorus (P) diffusion threaten the fresh water quality of the Three Gorges Reservoir area of China. A 10-year field trial on sloping citrus lands was conducted to evaluate five protection methods for reducing N and P losses: 1) intercropping with perennial white clover (CW); 2) straw mulching of the soil surface (CS); 3) intercropping with yellow daylily contour hedgerows (CH); 4) an impermeable membrane buried in the soil along the contour lines (CM); and 5) intercropping with a rotation of wheat and peanut (CWP). An area of conventional citrus management was also maintained as the control (CK). The results showed that CM and CH were the most effective methods for reducing surface runoff. The sediment yield were reduced at the highest rate by CW and CH and was also significantly reduced by CS. Reduced runoff volume and sediment yield were the crucial mechanism for the reductions in N and P losses. Compared with the control, CW, CS, CH, and CM reduced annual runoff by 9%, 13%, 25%, and 30%, sediment yield by 77%, 55%, 71%, and 28%, N loss by 10%, 23% 36%, and 37%, and P loss by 39%, 31%, 27%, and 25%, respectively. CW, CS, CH, and CM were effective in reducing N and P losses from the sloping citrus land. However, over the long-term, surface soil nutrient accumulation in CW, CS, and CH diminished the benefit of those methods in reducing N and P losses. In addition, CWP increased soil erosion and nutrient loss, which showed that citrus intercropping with other crops was an unsuitable method for citrus sloping land in the Three Gorges area.     

Effects of land use on soil erosion and nutrient loss in the Three Gorges Reservoir Area, China

Abstract. By comparing field measurements from 1989, 1997, and 1998, the differences between farmland (sloping farmland, sloping farmland with contour cultivation, terraced farmland) and orchard (terraced orchard, unterraced orchard), in the Three Gorges Reservoir Area, were significant for runoff ( P <0.01), erosion ( P <0.05) and nutrient loss ( P <0.05). Taking into account economic costs and environmental influences, reasonable and sustainable land use on slopes of 25° in the Three Gorges Reservoir Area should be unterraced orchard.     

添加水稻秸秆对不同类型土壤团聚体分布和稳定性的影响

以不同类型土壤(红壤、潮土、砂姜黑土)为研究对象,通过室内模拟试验,研究水稻秸秆添加对3种类型土壤水稳性团聚体分布及稳定性的影响。培养温度为28℃,培养时间为120d。研究结果表明:未添加水稻秸秆的3种类型土壤(对照组),微团聚体(250μm)占主体,2 000μm粒级水稳性团聚体含量最少。与对照相比,添加水稻秸秆后促使2 000μm粒级水稳性团聚体显著增加(p0.05),大团聚体(250μm)占主体。红壤、潮土、砂姜黑土试验组250μm水稳性团聚体比对照组增加的比例分别为35.6%,41.1%,22.0%,潮土的增加比例最为明显。3种类型土壤水稳性团聚体的平均重量直径(MWD),几何平均直径(GMD)显著增加(p0.05),分形维数(D)值、土壤不稳定团粒指数(ELT)显著减少,土壤结构和抗侵蚀能力明显得到改善,潮土的稳定性指标变化最为明显,团聚体结构改善效果最好。3种类型土壤0.25mm(R0.25)水稳性团聚体含量与GMD,MWD间呈极显著正相关关系(p0.001)。     

幼龄果园坡耕地保护性耕作的水土保持效果

随着农业产业结构调整,滇西南地区新植果园不断增多,水土流失及土壤退化成为该区域内普遍存在的重要生态环境问题.为提供切实可行的耕作技术指导,保护生态环境安全,本研究以滇西南边境地区坡耕地幼龄果园为对象,通过测定3种不同耕作措施(传统耕作、秸秆覆盖和生物覆盖)下的土壤养分状况、地表径流量和土壤流失量,研究不同保护性耕作模式的水土保持效果及作用机理.结果表明:秸秆覆盖和生物覆盖均能改善土壤养分状况,减少水土流失.相比于传统耕作,其他2种保护性耕作模式的土壤有机质、全氮和全钾质量分数增加了14％以上,径流量减少20％左右,土壤流失量减少10％ ～ 30％,总养分流失减少20％～30％.其中,生物覆盖模式水土保持效果更为显著,而且,随着试验时间推进,秸秆覆盖和生物覆盖模式的水土保持效果有明显增加的趋势.     

渭北旱塬管理措施对冬小麦地土壤剖面物理性状的影响

【目的】研究黄土高原旱作农业区不同施肥覆盖措施对冬小麦地0—40 cm土壤剖面物理性质的影响,可为保持良好的土壤物理性状,探求适合渭北旱塬可持续的田间管理措施提供参考。【方法】基于设在渭北旱塬15年的田间定位试验,选取NP (N 150 kg/hm^2+P 75 kg/hm^2)、NPK (NP+K 30 kg/hm^2)、NPB (NP+biochar 14.0t/hm^2)、NPFFT (NP配合地膜夏闲期覆盖)、NPFGT (NP配合地膜生育期覆盖)和NPFWT (NP配合地膜全年覆盖)共6个处理。于2017年冬小麦收获期采集剖面土样,对0—10 cm、10—20 cm、20—30 cm和30—40 cm土层土壤含水量、土壤容重、饱和导水率和水稳定性团聚体等相关土壤物理性质进行测定与分析。【结果】与NP相比,NPK处理降低了收获期0—20 cm土壤容重,增加了耕层土壤总孔隙度和0—40 cm土层> 2 mm水稳定性团聚体含量,0—10 cm土层> 2 mm水稳定性团聚体含量显著提高了1.3倍(P <0.05);NPB处理,收获期耕层土壤容重降低,土壤总孔隙度增加,表层土壤饱和导水率显著降低27.9%,剖面土壤含水量和> 2 mm水稳定性团聚体含量均增加,且表层> 2 mm水稳定性团聚体含量显著提高了1.0倍;NPFFT处理收获期剖面土壤含水量降低,耕层土壤容重增加,总孔隙度降低;NPFGT处理收获期耕层土壤容重和剖面土壤含水量均增加,耕层总孔隙度降低,剖面土壤饱和导水率降低,尤其表层显著降低60.2%;NPFWT处理收获期耕层土壤容重增加,总孔隙度降低,表层土壤饱和导水率降低,但10—40 cm土壤饱和导水率平均提高57.5%,剖面土壤含水量、> 2 mm水稳定性团聚体含量、平均重量直径和几何平均直径均增加。受当地传统耕作深度的影响,不同施肥覆盖措施对土壤容重、饱和导水率和孔隙度的影响主要集中在0—20 cm土层,对20—40 cm土层影响较小。【结论】在氮磷肥配施的基础上,增施钾肥、生物炭和地膜全年覆盖均有利于改善试验农田土壤物理性质,但从经济投入和对土壤物理性状改良程度方面考虑,增施钾肥和地膜全年覆盖这两种处理是保持渭北旱塬良好土壤剖面物理性质的有效措施。     

三峡库区耕地城镇化及城镇扩展测度

根据1975、1987、1995、2000和2005年的遥感影像解译出的城镇用地数据,分析了城镇扩展过程中耕地占用的规律,采用城镇用地扩展强度、城镇用地扩展极核、城镇用地扩展类型、城镇用地扩展紧凑度、城镇用地分维数等理论模型从数量上对研究区城镇用地的扩展进行了对比分析,然后采用缓冲区分析从空间上对研究区在不同缓冲区带内的扩展轨迹开展了对比分析。研究结果表明耕地占用较多的是重庆市区、渝北区;受重庆市区和渝北区生长极核的影响,邻近区县的扩展强度比较大;总的来看其扩展平稳有序,属紧凑填充式;缓冲区分析对城镇扩展的轨迹研究是有效的,在研究区的第二缓冲带内的城镇扩展的强度是较大的。对研究区1975～2005年期间城镇用地对耕地占用情况及扩展的空间模式的分析,有利于控制未来城镇化对耕地的占用,把握城市化进程所处的阶段及预测城市的未来发展趋势。     

三峡重庆库区柑橘园磷素平衡状况研究

以三峡重庆库区柑橘种植农户调查资料和土壤测试分析数据为基础,从区域角度出发,分析了柑橘园生产体系中的磷肥施用特征和磷素平衡状况.结果表明,果园磷肥平均投入量为P 228.8 kg/hm2,主要来源于复合肥和普钙;其中通过有机肥投入的磷素水平为P 32.7 kg/hm2,主要来源于畜禽粪尿.柑橘园的总体磷盈余量为P l0...     

三峡重庆库区柑橘园氮素平衡状况研究

以三峡重庆库区柑橘种植农户调研资料和土壤测试分析数据为基础,从区域角度出发,分析了柑橘园生产体系中的氮肥施用特征和氮素平衡状况。结果表明: 果园氮肥投入量为409.7 kg/hm2,主要来源于复合肥和尿素; 其中通过有机肥投入的氮素水平为 76.51 kg/hm2,主要来源于畜禽粪尿; 柑橘园的总体氮盈余量为 363.9 kg/hm2,盈余量以奉节、江津和永川区较高; 果园氮素投入与氮养分盈余量之间存在极显著的正相关关系。说明过量施用氮肥是氮盈余量高的主要原因。随着氮盈余量增加,果园土壤全氮呈增加趋势,而土壤C/N呈下降趋势, 氮素盈余对土壤全氮的影响大于土壤有机质的影响。     

玉米整秆带状覆盖量对旱地冬小麦土壤水分利用的影响

为明确西北黄土高原半干旱雨养条件下,玉米整秆带状覆盖适宜的秸秆覆盖量,以露地种植为对照(CK),研究了4种覆盖量(T_1:6 750kg/hm~2,T_2:9 000kg/hm~2,T_3:11 250kg/hm~2,T_4:13 500kg/hm~2)对旱地冬小麦土壤水分和产量的影响。结果表明:4种覆盖量较CK显著增产12.1%~23.3%,提高水分利用效率13.4%~26.8%。产量与单位面积穗数呈显著正相关(r=0.937),整秆带状覆盖较CK可显著(除T_3)提高单位面积穗数10.4%~19.0%,以T_2单位面积穗数最高。全生育期0—200cm土层平均含水量4种覆盖量均显著高于CK,较CK高0.7~1.0个百分点,以T_1土壤水分状况最好。4种覆盖量可显著改善灌浆前0—200cm土壤墒情,但从灌浆期开始0—90cm土壤含水量普遍不如CK。4种覆盖量间,以T_2全生育期0—60cm土壤墒情最好,且其增产和提高水分利用效率效果也最显著。