LONG‐TERM LAND USE INFLUENCES SOIL MICROBIAL BIOMASS P AND S,PHOSPHATASE AND ARYLSULFATASE ACTIVITIES,AND S MINERALIZATION IN A BRAZILIAN OXISOL

Land use choices differentially affect soil physical and biological properties. Tillage choices in particular affect soil erosion, the retention of soil organic matter, and the biological activity that organic matter supports. The present study evaluated the consequences of different cropping and tillage systems (undisturbed forest, coffee plantation, conventional, and no‐tillage row cropping) for soil microbial indicators and sulfur mineralization after 24 years of cropping on an Oxisol (Typic Haplorthox) in an experimental area at Londrina, Brazil. Soil samples were taken at 0–5, 5–10, and 10–20 cm depths and evaluated for microbial biomass P and S, S mineralization, and phosphatase and arylsulfatase activities. Land use affected microbial biomass P and S, and enzyme activity at all depths studied. The cultivated sites had lower values of microbial activity than the undisturbed forested site. Although the coffee site was not tilled and had high organic carbon content, there was low microbial activity, probably due to higher soil acidity and Al content. The estimates of pool stock for microbial P and annual P flux through the soil microbial biomass suggest that these pools are large enough to significantly affect plant nutrient availability. The greater microbial biomass and activity under forested and no‐tillage sites may be attributed, at least partially, to higher organic matter content. The soil microbial variables examined proved to be strong indicators of soil sustainability. Copyright © 2013 John Wiley & Sons, Ltd.     

Maintaining soil fertility under increasing land use pressure in the Middle Mountains of Nepal

Abstract. Nepal is facing a serious problem of being unable to maintain soil fertility in agriculture and forestry. Land use practices initiated over the past 10–15 years have resulted in insufficient nutrient inputs, while biomass use and production have increased. Changes in forest soil fertility have resulted from intensive use of forest biomass for animal feed and collection of forest litter for use in agriculture. The agricultural fertility changes have resulted from intensifying annual crop rotations from 1.5 to 2.5 crops and insufficient inputs. The removal of biomass from the forest has curtailed the natural organic cycle by virtually eliminating nutrient inputs.
The soils are very acidic and have little C, N, P and exchangeable bases, but have large amounts of active iron. Basic nutrients are not sustained in agriculture and differences in inputs and management between irrigated and rainfed agricultural systems are becoming visible. Irrigated fields show the largest cation content because of input from irrigation water. Rainfed agricultural sites, which receive the most nutrients (fertilizers and manure), have the highest pH values and C and N contents. All soil fertility conditions are marginal and put into question the long-term sustainability of current levels of production. Alterations in the cropping intensity are needed and the introduction of nitrogen fixing trees and crops seems to be the most viable option towards sustainability.     

Soil sustainability changes in organic crop rotations with diverse crop species and the share of legumes

There have been few long-term field studies on greenhouse gases measurement in organic crop rotations under temperate climatic conditions. Little is known about the extent to which the share of legumes in a crop rotation of organic farming affects the potentials for CO₂ emission and soil organic carbon sequestration. The current study was aimed to investigate soil physicochemical state and soil net CO₂ exchange rate in diverse organic crop rotations with different crop species and proportions of legumes. Four 5-year duration crop rotations were investigated. The best soil sustainability of the arable layer was found in a crop rotation enriched with red clover (Trifolium pratense L.). This rotation resulted in the highest soil mesoporosity and the lowest microporosity, ensured the best supply of plant-available water and revealed high soil resistance to dry conditions. Red clover secured the highest soil organic C sequestration, caused the increase in reserves of total N and available K, and slackened the decrease of soil-available P sources. Red clover-based cropping system exhibited the highest soil net CO₂ exchange rate during five experimental years. The effect of crop rotation, consisting of phacelia (Phacelia tanacetifolia Benth.), peas (Pisum sativum L.) and yellow lupin (Lupinus luteus L.), on soil sustainability was weaker than the effect of rotation with red clover. Non-legume rotations, i.e. binary (two-crop) rotation and the crop rotation involving four spring and one winter species, can be regarded as miners of soil nutrient resources rather than contributors. These rotations did not promote soil sustainability because the soil lost large amounts of macronutrients and caused 26–33% lower soil net CO₂ exchange rate, compared with leguminous rotations. For future, it could be recommended for ecological farming to rely more on crop rotations with red clover to improve ecosystems functioning.     

Role of Soil Organic Matter in Maintaining Sustainability of Cropping Systems

Soil organic matter (SOM) has long been recognized as an important indicator of soil productivity. The SOM refers to the organic fraction of the soil exclusive of undecayed plant and animal residues. It plays a crucial role in maintaining sustainability of cropping systems by improving soil physical (texture, structure, bulk density, and water-holding capacity), chemical (nutrient availability, cation exchange capacity, reduced aluminum toxicity, and allelopathy), and biological (nitrogen mineralization bacteria, dinitrogen fixation, mycorrhizae fungi, and microbial biomass) properties. The preservation of SOM is crucial to ensure long-term sustainability of agricultural ecosystems. Improvement/preservation of soil organic matter can be achieved by adopting appropriate soil and crop management practices. These practices include conservation tillage, crop rotation, use of organic manures, increasing cropping intensity, use of adequate rate of chemical fertilizers, incorporation of crop residues, liming acidic soils, and keeping land under pasture. Organic matter can adsorb heavy metals in the soils, which reduce toxicity of these metals to plants and reduce their escape to ground water. Similarly, SOM also adsorbs herbicides, which may inhibit contamination of surface and ground water. Furthermore, SOM also functions as a sink to organic carbon and mitigates carbon dioxide (CO₂) gas escape to the environment. Globally, soil organic matter contains about three times as much carbon as found in the world's vegetation. Hence, organic matter plays a critical role in the global carbon balance that is thought to be the major factor affecting global warming. Overall, adequate amounts of soil organic matter maintain soil quality, preserve sustainability of cropping systems, and reduce environmental pollution.     

相比其他传统作物作为生物能源作物柳枝稷种植土壤上的有机碳库研究

Switchgrass (Panicum virgatum L.) has been proposed as a sustainable bioenergy crop because of its high yield potential, adaptation to marginal sites, and tolerance to water and nutrient limitations. A better understanding of the potential effects of biomass energy crop production practices on soil biological properties and organic matter dynamics is critical to its production. Our objective was to evaluate changes in C pools under a warm-season perennial switchgrass in different soils compared to typically-grown crops collected at College Station, Dallas, and Stephenville, TX in February 2001. Sampling depths were 0-5, 5-15, and 15-30 cm. Switchgrass increased soil organic C (SOC), soil microbial biomass C (SMBC), mineralizable C, and particulate organic matter C (POM-C) compared to conventional cropping systems. Soil C concentrations were in the order: long-term coastal bermudagrass [Cynodon dactylon (L.) Pers.]> switchgrass or kleingrass (Panicum coloratum L.) planted in 1992> switchgrass 1997> conventional cropping systems. Soil C concentrations tended to increase with increasing clay content. Greater microbial biomass C followed the order of Dallas> College Station> Stephenville, and ranged from approximately 180 mg C kg-1 soil at Stephenville to 1 900 mg C kg-1 soil at Dallas. Particulate organic C was more sensitive than other fractions to management, increasing as much as 6-fold under long-term coastal bermudagrass compared to conventional cropping systems. Our study indicated that conversion of conventional cropping systems into switchgrass production can sequestrate more SOC and improve soil biological properties in the southern USA.     

Agronomic Practices at Low Environmental Impact for Durum Wheat in Mediterranean Conditions

The application of conservative agricultural practices such as crop rotation, shallow tillage, and organic fertilizer could usefully sustain crop yield and increase soil fertility, thus playing an important role in the sustainable agriculture. This study was conducted to determine the effects of conservative agronomic practices on yield and quality of wheat. The effects of these practices on soil fertility were further investigated in this four-year study (2005–2008). Two cropping systems, durum wheat in continuous cropping, and in two-year rotation with leguminous crops, were investigated at Foggia (Southern Italy) in rain-fed conditions. Within each cropping system, two levels of crop management were compared: i) conventional, characterized by a higher soil tillage management and mineral fertilizers application; ii) conservative, with a lower soil tillage management and organic-mineral fertilizers. The seasonal weather greatly affected the wheat yield and quality, inducing lower production in years that were characterized by unfavorable climatic conditions. This trend was found when the conventional treatment was applied, both in continuous cropping and rotations. The effects of cropping systems and crop management pointed out the positive role played by the leguminous crops (common vetch and chickpea) in crop rotation. This introduction improved wheat yield in rotation (6.47% compared to the continuous cropping), improved grain protein content (5.88%), and reduced the productive gap between conventional and conservative treatments (9.24 and 14.14% of the wheat in rotation and continuous cropping, respectively). Conversely, the effects of cropping systems and crop management on soil fertility were not very high, since the differences found at the end of the study in total nitrogen values were poor. However, total organic carbon (16.04 and 17.58% for cropping system and crop management, respectively) and available phosphorus values (11.30 and 7.43%) depend on root organic matter contribution, plant biomass residues, and fertilizations. The suitable crop rotation and the sustainable crop management appear important agronomical practices to improve yield and quality of wheat, and may reduce the environmental risks resulting from conventional intensive cropping systems.     

Soil organic carbon and nitrogen fractions and water‐stable aggregation as affected by cropping and grassland reclamation in an arid sub‐alpine soil

This paper investigates effects of cropping abandonment and perennial grass growing on soil organic C and N pools and aggregate stability, by comparing soils under native grassland, crop cultivation, perennial grass growing and cropping abandonment, in degraded cropland at a sub‐alpine site in north‐western China. The pools of total and particulate organic C (115 and 37 Mg ha⁻¹) in the 0–30 cm soil layer of native grassland were reduced by 31 and 54% after 30 years of crop cultivation. After 4 years of conversion from cropland to perennial grass growing total and particulate organic C pools were increased by 29 and 56%, whereas 4 year cropping abandonment increased particulate organic C by 36%. Rapid increases in total and particulate N were also found in perennial grass growing and cropping abandonment soils. The native grassland soil and soils of cropping abandonment and perennial grass growing had higher carbohydrate C concentrations in the 0–10 cm layer than the cropped soil. The rapid recovery of particulate organic fraction and carbohydrates in the re‐vegetated soils were probably due to higher plant biomass inputs and lower organic matter decomposition compared with those in the cropped soil. Aggregate stability of the 0–30 cm soil layer was significantly decreased by crop cultivation but showed a good recovery after 4 year re‐vegetations. This study suggests that reduction of soil organic matter and aggregate stability under crop cultivation may be remedied by cropping abandonment or perennial grass growing. Copyright © 2008 John Wiley & Sons, Ltd.     

Lasting effects of soil health improvements with management changes in cotton-based cropping systems in a sandy soil

The soil microbial component is essential for sustainable agricultural systems and soil health. This study evaluated the lasting impacts of 5 years of soil health improvements from alternative cropping systems compared to intensively tilled continuous cotton (Cont. Ctn) in a low organic matter sandy soil. Our previous study (phase I) evaluated soil health microbial indicators (microbial biomass, community composition and enzyme activities) during 5 years (2003-2007) when more plant residue was returned to the soil by rotating cotton (primary cash crop) with grain sorghum (secondary cash crop) with and without a rye winter cover crop (Ctn-Rye-Sg and Sg-Ctn) or with a system that involved no cash crop and returned maximum biomass to the soil (3 times residue vs Cont. Ctn) with a sorghum x sudangrass hybrid with winter rye cover (SSd-Rye). The current study (phase II) addressed what happens to the microbial component (same microbial indicators) once the management is changed to more cotton production the following 3 years (i.e., cotton was planted 2 out of 3 years in SSd-Rye and was grown for 3 years in Ctn-Rye-Sg). During the first year of phase II (2008), all plots were planted in cotton, and higher cotton yields in SSd-Rye (108–150%) corresponded to microbial trends found in the original rotations (SSd-Rye > Sg-Ctn = Ctn-Rye-Sg). In regard to microbial indicators, the most significant trends with reintroduction of cotton and increase in tillage were a reduction in fungal FAME (fatty acid methyl esters) indicators with a lower ratio of fungi to bacteria and much lower AMF (15.1 to 3.98% of arbuscular mycorrhizal fungi), and less biogeochemical cycling potential of soil according to several enzyme activities (by as much as 50%). At the end of phase II (2010), Ctn-Rye-Sg and SSd-Rye were still found to have higher microbial biomass and enzyme activities (1.5 times both measurements except for phosphodiesterase) compared to continuous cotton. This study demonstrates the vulnerability of microbial communities in sandy soils, which requires agroecosystems that will support biomass incorporation (e.g., sorghum and cover crops) when possible in order to sustain essential functions and overall soil health.     

Changes in soil properties in southern Beijing Municipality following land reform

Following land reform in China in the early 1980s, farm management practices, such as the type of crops grown and their rotations, intensity of cropping and fertilizer and pesticide use, underwent drastic changes. To investigate how these changes affected soil properties and ultimately the sustainability of agricultural production, a case study was conducted in Daxing County (southern Beijing Municipality). Soil in the Daxing area was sampled in 1982 at the onset of land reform and again in 2000. Surface soil (0–20 cm) samples were collected and analyzed for organic matter (OM), total nitrogen (TN), and available N (AN), P (AP) and K (AK) contents. The soil OM, TN, AN, and AP all increased significantly while AK decreased slightly, but significantly, for the sampling area over the 18-year study period. Increased crop yield (higher biomass production) with increasing fertilizer application combined with soil conservation measures that have retained more crop residue on land, are responsible for the increases in soil OM, N and P concentrations. However, the slight decreases in AK reflect the increased cropping intensity and low AK supplying power of these coarse textured soils as well as the low K fertilizer input.     

Legume–barley intercropping stimulates soil N supply and crop yield in the succeeding durum wheat in a rotation under rainfed conditions

Legume–cereal intercropping is increasingly being appreciated in dryland areas, where severe climatic conditions and intensive agricultural practices, generally dominated by continuous cereal cultivation, determine depletion of soil nutrient resources and decline of soil fertility. This research aimed to assess whether and to what extent a newly introduced legume-based intercropping system is able to ameliorate the biological fertility status of an arable soil in a way that is still noticeable during the succeeding durum wheat cropping season in terms of changes in bacterial community structure, soil C and N pools, and crop yield. A field experiment was carried out under rainfed conditions in Southern Italy on a sandy clay loam soil cultivated with durum wheat following in the rotation a recently established grain legume (pea, faba bean)–barley intercropping. Soil chemical, biochemical and eco-physiological variables together with compositional shifts in the bacterial community structure by LH-PCR fingerprinting were determined at four sampling times during the durum wheat cropping season. Soil fertility was estimated by using a revised version of the biological fertility index. Results showed that even though the microbial biomass was significantly altered, the preceding legume intercrops stimulated C-related functional variables thus leading to an increased release of mineral N, which was larger in crop treatments succeeding pea-based than faba bean-based intercropping. The increased N made available in soil enabled the succeeding durum wheat to achieve an adequate grain yield with a reduced N-fertilizer use. Soil type and environmental conditions rather than crop treatments were major determinants of bacterial community structure. The biological fertility status was not varied, suggesting that in intensively managed rainfed areas long-term crop rotations with intercropped legumes are needed to consistently ameliorate it.     

”The principles of rational agriculture” by Albrecht Daniel Thaer (1752–1828). An approach to the sustainability of cropping systems at the beginning of the 19th century

The identification of quantitative fertility indicators for evaluating the sustainability of cropping and farming systems has become a major issue. This question has been extensively studied by the German agronomist Albrecht Daniel Thaer at the beginning of the 19^h century. In this paper Thaer's work is set in its historical background, from the end of the 16^th century (Palissy, 1580) to the middle of the 19^th century (Liebig, 1840). Then the paper focuses on Thaer's quantitative and complex fertility scale (expressed in “fertility degrees”), which was based on soil properties, on the requirement of nutrients by plants, and on the cropping system (including crop rotation). Thaer expressed soil fertility and economic results as a function of rye production in “scheffel of rye per journal” (ca. 200 kg per hectare). He also proposed a scale to describe the intrinsic fertility of soil. Thaer used this approach to assess the effect of major German cropping systems on soil fertility. He applied it to eight theoretical systems and nine existing systems in a true modeling approach. Thaer completed the fertility evaluation for the nine existing systems with a detailed economical analysis commenting the limits and potentialities of each system. Thaer's approach was used with success during half a century as it combined numerous empirical findings on soils and fertilization with organic substances in a sophisticated model. Unfortunately and despite effective practical applications, the scientific foundations of Thaer's “Humus Theory” proved definitively false as soon as 1840 when Sprengel and Liebig published on mineral nutrition of plants. Thaer's work deserves to be rediscovered since it approaches the modern issue of the sustainability of cropping and farming systems.     

加工番茄连作对土壤理化性状及微生物量的影响

通过在石河子大学农学院试验站开展加工番茄连作定点微区试验,研究了不同连作处理(种植1 a、连作3 a、5 a和7 a)对新疆加工番茄土壤理化性状、微生物生物量和酶活性的影响。结果表明,随着连作年限的延长,土壤p H升高,全磷、速效磷及全钾含量呈先升后降的趋势,土壤容重无明显变化。连作7 a时土壤有机质、全氮及速效钾含量较对照分别下降了8%、21%和29%(p0.05)。土壤微生物量碳(SMBC)、微生物量氮(SMBN)和微生物商(q MB)呈显著下降趋势,与对照相比分别降低了52.3%、78.8%和48.2%(p0.01);微生物量磷(SMBP)呈先升后降趋势,连作3a时,SMBP含量达到最大值,是对照的1.65倍(p0.01)。土壤过氧化氢酶活性呈显著升高趋势,而脲酶、蔗糖酶、多酚氧化酶及磷酸酶活性的变化则相反。连作导致加工番茄产量显著下降,连作7 a时产量下降达34%(p0.01)。相关分析表明,p H、微生物量、q MB、酶活性及养分之间相关性极为密切,说明土壤微生物量和酶活性相结合,可以反映土壤质量的变化。加工番茄连作导致土壤p H和电导率升高,显著抑制了土壤微生物活性,降低了土壤肥力,最终造成产量下降,连作障碍明显。     

Impact of long-term organic and inorganic nutrient managements on the biological properties and eubacterial community diversity of the Indian semi-arid Alfisol

Intensive cropping with limited nutrient management options in low fertile semi-arid tropical soils will have agricultural sustainability problems in future. A better understanding of soil variables as influenced by long-term nutrient amendments could lead to the identification of more precise indicators to monitor soil fertility that would promote sustainability. Long-term nutrient experiment in semi-arid Alfisol at Coimbatore, India was investigated in two successive years, 2009 and 2010 to assess the enduring effects of organic (OM) and inorganic (IC) nutrient managements on soil variables. The organic amendments induced higher microbial population and enzyme activity compared to IC and control soils. The principal component analysis of observed variables revealed that soil organic carbon, microbial biomass carbon (MBC), dehydrogenase and alkaline phosphatase activity and diazotrophs population could be the possible indicators for predicting soil fertility resulting from long-term nutrient managements. The eubacterial community profile assessed by 16S rRNA gene sequence polymorphism revealed that the abundance and relative ratio of phyla belonging to Proteobacteria, Actinobacteria, Acidobacteria and Firmicutes were considerably affected due to either organic manures or inorganic fertilizers, and organic nutrient management favours bacterial community diversity. These results emphasize the importance of organic nutrient management to maintain soil biological properties in semi-arid Alfisol.     

坡耕地不同水土保持措施下的养分平衡和土壤肥力变化

在贵州省罗甸县坡耕地上布置长期定位试验 ,研究几种水土保持措施对作物产量和土壤肥力变化的影响。9年的测试结果表明 ,在旱坡耕地上 ,水土流失是造成坡地地力下降、养分损失 ,的主要原因。未采用水土保持措施的坡地种植 ,因水土流失产生的全氮、全磷、有效钾损失 ,分别占总养分消耗量的 5 3.0 % ,6 7.6 %和 19.0 % ,相当于施入土壤的氮素化肥 ,施入的有机和无机磷素 ,有机质的损失与施入的有机肥中有机质含量相当 ,土壤全氮、有机质和有效钾含量趋于下降 ,全磷维持在较低的水平。采取水土保持措施后 ,这些土壤养分可维持平衡或在土壤中逐步积累 ,试验中的植物篱水保处理 ,9年玉米产量平均增产 8.6 % ,并趋于逐年上升。长期的试验证明 ,采用适宜的水土保持措施可提高地力 ,增加产量 ,实现坡耕地的可持续利用     

Long-term effects of crop rotation and different fertilization systems on soil fertility and productivity

The effects of crop rotation and fertilization systems on yield and soil fertility parameters have been investigated in a long-term field trial established in southeast Norway in 1953. The results indicate the small differences between crop rotations and different fertilization systems in yield and soil fertility parameters; the decreasing trend in soil organic carbon (SOC) (from 3.8 to 3.7%) and increasing trend of N with time (from 0.32 to 0.36%) and, as a result, the decreasing trend in C/N ratio (from 12 to 10).     

Long‐term effects of tillage,nutrient application and crop rotation on soil organic matter quality assessed by NMR spectroscopy

Crop and land management practices affect both the quality and quantity of soil organic matter (SOM) and hence are driving forces for soil organic carbon (SOC) sequestration. The objective of this study was to assess the long‐term effects of tillage, fertilizer application and crop rotation on SOC in an agricultural area of southern Norway, where a soil fertility and crop rotation experiment was initiated in 1953 and a second experiment on tillage practices was initiated in 1983. The first experiment comprised 6‐yr crop rotations with cereals only and 2‐yr cereal and 4‐yr grass rotations with recommended (base) and more than the recommended (above base) fertilizer application rates; the second experiment dealt with autumn‐ploughed (conventional‐till) plots and direct‐drilled plots (no‐till). Soil samples at 0–10 and 10–30 cm depths were collected in autumn 2009 and analysed for their C and N contents. The quality of SOM in the top layer was determined by ¹³C solid‐state NMR spectroscopy. The SOC stock did not differ significantly because of rotation or fertilizer application types, even after 56 yr. However, the no‐till system showed a significantly higher SOC stock than the conventional‐till system at the 0–10 cm depth after the 26 yr of experiment, but it was not significantly different at the 10–30 cm depth. In terms of quality, SOM was found to differ by tillage type, rate of fertilizer application and crop rotation. The no‐till system showed an abundance of O‐alkyl C, while conventional‐till system indicated an apparently indirect enrichment in alkyl C, suggesting a more advanced stage of SOM decomposition. The long‐term quantitative and qualitative effects on SOM suggest that adopting a no‐tillage system and including grass in crop rotation and farmyard manure in fertilizer application may contribute to preserve soil fertility and mitigate climate change.     

长期不均衡施肥对紫色土肥力质量的影响

利用长期定位试验研究了不均衡施肥对紫色土土壤肥力、肥料利用率和养分平衡状况的影响。结果表明,连续11年不施肥,耕层土壤有机质和全氮含量降低,施用化肥的各个处理土壤有机质和氮素含量稳中有升,其中以NPK均衡施用增幅最大。所有施磷处理,土壤速效磷含量与试验前相比都有大幅度提高;无论施钾与否,土壤缓效钾含量均比试验前降低,稻草还田土壤缓效钾下降最少。不均衡施肥降低了肥料利用率和肥料的增产效果。每季施N.150kg/hm2,维持了土壤氮素肥力;每季施P2O560～75.kg/hm2,磷素都有赢余;除秸秆还田处理钾素有盈余外,其余各处理钾都亏缺。     

Conservation Tillage,Rotations, and Cover Crop Affecting Soil Quality in the Tennessee Valley: Particulate Organic Matter,Organic Matter,and Microbial Biomass

Abstract

The impact of conservation tillage, crop rotation, and cover cropping on soil‐quality indicators was evaluated in a long‐term experiment for cotton. Compared to conventional‐tillage cotton, other treatments had 3.4 to 7.7 Mg ha^?1 more carbon (C) over all soil depths. The particulate organic matter C (POMc) accounts for 29 to 48 and 16 to 22% of soil organic C (SOC) for the 0‐ to 3‐and 3‐ to 6‐cm depths, respectively. Tillage had a strongth influence on POMc within the 0‐ to 3‐cm depth, but cropping intensity and cover crop did not affect POMc. A large stratification for microbial biomass was observed varing from 221 to 434 and 63 to 110 mg kg^?1 within depth of 0–3 and 12–24 cm respectively. The microbial biomass is a more sensitive indicator (compared to SOC) of management impacts, showing clear effect of tillage, rotation, and cropping intensity. The no‐tillage cotton double‐cropped wheat/soybean system that combined high cropping intensity and crop rotation provided the best soil quality.     

不同培肥模式对茶园土壤微生物活性和群落结构的影响

以闽东地区红黄壤茶园定位实验地为对象,通过测定6种不同施肥处理土壤微生物学特性,研究不同培肥对土壤微生物特性和生物化学过程的影响,阐明各指标间的相互关系.结果表明,除了单施无机肥处理外,半量化肥+半量有机肥、全量有机肥、全量化肥+豆科绿肥以及半量化肥+半量有机肥+豆科绿肥等的培肥方式均不同程度提高了土壤有机质,可培养微生物数量,微生物量碳、氮含量及土壤酶活性,尤以半量无机肥+半量有机肥+豆科牧草的培肥模式增幅更为明显,而单施无机肥不利于微生物的生长、酶活性的提高和维持生态系统的稳定性.微生物群落磷脂脂肪酸(PLFAs)标记主成分分析显示,各种不同施肥方式使微生物群落结构发生改变.相关分析表明,微生物量与可培养微生物数量、微生物磷脂脂肪酸含量之间的相关性明显高于微生物量与各种酶活性之间的相关性,说明微生物数量大小对微生物群落结构的影响大于对酶活性功能的影响.研究也表明土壤各微生物指标能从不同方面反映土壤肥力水平,所以采用各种不同的方法能更客观地评价闽东地区茶园红黄壤质量的优劣.     

Green manure rotation and application increase rice yield and soil carbon in the Yangtze River valley of China

The addition of organic matter via green manure rotation with rice is considered a smart agricultural practice to maintain soil productivity and support environmental sustainability. However, few studies have quantitatively assessed the impact of green manure rotation and application on the interactions between agronomic management practice, soil fertility, and crop production. In this study, 800 pairs of data from 108 studies conducted in the agricultural region of the Yangtze River, China were...