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1.
Abstract

Many countries have reported that green revolution (GR) technology caused some adverse effects on agricultural lands, but there is no research on the effects of GR in Indonesia. To evaluate the effect of GR technology on sawah soil in Indonesia, a comparative study between seedfarms, where GR technology has been continuously applied, and non-seedfarms was conducted in Java as a pioneer place of GR technology in Indonesia and, in particular, on the carbon and nitrogen status in sawah soils. The term sawah refers to a leveled and bounded rice field with an inlet and outlet for irrigation and drainage. Soil samples collected by Kawaguchi and Kyuma in 1970 and new samples taken in 2003 from the same sites or sites close to the 1970 sampling sites were analyzed and compared. During the period 1970–2003 the land-use pattern of sawah in seedfarms and non-seedfarms did not change, but cultivation intensity increased. The results showed that total carbon (TC) and total nitrogen (TN) contents significantly increased from 31.90 to 40.42 Mg ha?1 and from 3.04 to 3.97 Mg ha?1, respectively, and TC and TN were mostly found accumulated in the surface soil layer. The difference in land management practices between seedfarms and non-seedfarms affected the change in TC and TN content in the 0–20 cm soil layer from 1970 to 2003. In seedfarms, where rice had been planted in a monoculture system, TC and TN contents in the 0–20 cm soil layer increased from 34.50 to 39.24 Mg ha?1 and from 3.16 to 3.95 Mg ha?1, respectively. In non-seedfarms, TC and TN increased more than in seedfarms from 29.77 to 41.37 Mg ha?1 and from 2.94 to 3.98 Mg ha?1, respectively. Within the 0–100 cm soil layer, TC and TN increased from 92.68 to 112.83 Mg ha?1 and from 9.34 to 12.03 Mg ha?1 and from 79.60 to 114.86 Mg ha?1 and from 8.93 to 11.44 Mg ha?1 for seedfarms and non-seedfarms, respectively. No significant difference was observed between the two main soil types, Inceptisols and Vertisols, in Java. Intensive use of sawah over a long time may eliminate the original difference in the properties of these two soil types.  相似文献   

2.
A long term experiment (2005–2012) was conducted in rainfed semi-arid tropical Alfisol at Hayathnagar Research Farm of Central Research Institute for Dryland Agriculture, Hyderabad, India. The aim of this experiment was to study the long-term impacts of graded levels of surface crop residue application on carbon (C) pools, aggregate associated C, C lability index and their relationship with crop yield. The experiment was conducted in a randomized block design (RBD) with minimum tillage (MT). Experimental treatments comprised of four levels of surface application of sorghum crop residues (@ 0, 2, 4 and 6 t ha?1). The test crops, sorghum and cowpea, were grown in rotation yearly. Based on the pooled analysis of long term data (2005–2012), the study revealed that the surface application of sorghum residue @ 6 t ha?1 and 4 t ha?1 recorded 21% and 16% higher sorghum grain yields, respectively over control (no residue) whereas, the corresponding increase in the cowpea yield was 50% and 60%, respectively. Besides, the concentrations of soil organic carbon (SOC), inorganic carbon (IC), total carbon (TC), particulate organic carbon (POC) in the top surface soil (upper layer, 0–5cm depth) were found significantly higher than the sub-surface soil (lower layers, 5–15 cm depth) in all the treatments. Storage of soil C was assessed in soil aggregates fractions, and it was found that the smaller size aggregate fractions (0.053mm) contained significantly (p = 0.05) higher content of SOC compared to the large sized fractions (2 mm). The amount of very labile fraction of C extracted with 12 N H2SO4 was significantly higher (1.04 g kg?1) with the application of sorghum stover @ 6t ha-1 compared to other residue level treatments, in the 0-5 cm soil layer. The Lability Index (LI) increased with the increase in the amount of residues applied and was significantly higher in the surface soils compared to subsurface soil. The results of this study will be highly relevant and of significant value from the view point of managing SOC and its different pools in soil under abiotically stressed semiarid tropical Alfisols soils.  相似文献   

3.
Abstract: High soil acidity influences the availability of mineral nutrients and increases that of toxic aluminium (Al), which has a jeopardizing effect on plant growth. The objective of this research was to evaluate the effects of soil liming on the development of guava (Psidium guajava L.) plants, on soil chemical characteristics, and on fruit yield. The experiment was carried out at the Bebedouro Citrus Experimental Station, state of São Paulo, Brazil, in a Typic Hapludox soil, from August 1999 to March 2003. The treatments consisted of limestone dose: D0 = zero; D1 = half dose; D2 = total dose; D3 = 1.5 times the dose, and D4 = 2 times the dose to raise the V value to 70%. The doses corresponded to zero, 1.85, 3.71, 5.56, and 7.41 t ha?1 applied to the upper soil layer (0–30 cm deep) before planting. The results showed that liming caused an improvement in the evaluated soil chemical characteristics up to a depth of 60 cm in soil samples both in the line and between lines. The highest fruit yields were obtained when the base saturation reached a value of 55% in the line and 62% between the lines. Foliar levels of calcium (Ca) and magnesium (Mg) were 8.8 and 2.5 g kg?1, respectively. The highest limestone dose maintained the soil base saturation (at the layer of 0–20 cm) in the line close to 55% during at least 40 months after the incorporation of limestone.  相似文献   

4.
The tropical soil acidity is one of the main limiting factors for crop productivity. This study aimed to evaluate the effects of application of limestone dose to soil fertility, nutritional status of the crop, and productivity and quality of the fruits of mango, cultivar Keitt. The study was carried out at Selvíria, state of Mato Grosso Sul, Brazil, in a Typic Haplustox (pH in CaCl2 = 4.7), cultivated with mango cultivar Keitt grafted on Coquinho pattern in the production phase (13 years old). Treatments were composed of limestone doses (0, 1.55, 3.10, 4.65, and 6.20 t ha?1), arranged in blocks at random with three repetitions. The limestone was applied and incorporated in the surface layer of 0 to 5 cm deep in the total area. We evaluated the chemical attributes of the soil [pH, hydrogen (H+) aluminum (Al), calcium (Ca), magnesium (Mg), potassium (K), and sum of bases and base saturation] at 16 and 28 months after liming (layer 0 to 20 cm deep), the nutrition of plants at 12 months after liming, and quality of the fruit in two crop years. Liming promoted improvements in soil chemical attributes, reflected in the nutritional status, productivity, and quality of mango fruit. Also, there was a linear effect with the application of lime dose on the productivity of the fruit, but after the second year of evaluation.  相似文献   

5.
The objective of this study was to quantify the combined effects of long-term plant biomass retention/removal and environmental conditions on soil microbial biomass phosphorus (P), bioavailable P, and acid phosphomonoesterase activity. Topsoil samples (0–2.5 and 2.5–5 cm) were collected from replicate field-based plots that had been maintained under contrasting plant biomass retention and removal regime for 21 years. Samples were collected on 14 occasions over a 17-month period and assessed for microbial P, bioavailable P, and phosphomonoesterase activity. All P measurements were consistently and significantly higher under plant biomass retention compared with biomass removal. Temporal variations in microbial P and phosphomonoesterase activity were evident in top soil (0–2.5 cm) and were driven by environmental conditions, mainly soil moisture, rainfall, and potential evapotranspiration, while bioavailable P had no temporal variation. Detailed analysis of microbial P data for the top 2.5-cm soil depth revealed that annual P flux through this pool was two times greater under biomass retention (10.3 kg P ha?1 year?1) compared with plant biomass removal (5.0 kg P ha?1 year?1). Similar and consistent trends were observed in soil from 2.5- to 5-cm sampling depth; however, differences were not significant. The findings of this study confirm the importance of the microbial biomass in determining the bioavailability of P in temperate grassland systems.  相似文献   

6.
沙国良  陈宇轩  魏天兴  任康  郭鑫  傅彦超 《土壤》2022,54(6):1265-1273
为深入了解植被恢复对土壤碳库的影响，本研究选取黄土高原丘陵区草地、沙棘、油松、山杏和山杏油松混交林0~100 cm土壤为研究对象，运用随机森林模型等方法，探究黄土高原丘陵区典型退耕恢复植被有机碳（SOC）、无机碳（SIC）、全碳（TC）含量分布特征及其影响因素。结果表明：（1）研究区各恢复植被平均土壤全碳含量为1.685~1.898 g/kg，平均土壤有机碳含量山杏(0.368 g/kg)>草地(0.299 g/kg)>沙棘(0.250 g/kg)>油松(0.233 g/kg)>油松山杏混交(0.209 g/kg) ，平均土壤无机碳含量为平均土壤有机碳含量的5.6倍。（2）所有恢复植被土壤深层（60~100 cm）无机碳含量均无显著差异（P>0.05）。除油松外，各恢复植被表层（0~20 cm）土壤有机碳含量显著高于其他土层（P<0.05）。（3）坡向、坡度、海拔、土地利用类型、土壤含水量、土壤黏粒、速效磷和速效氮共解释了78%、24%和77%的SOC、SIC和TC含量变化，其中海拔、坡向和土壤含水量为研究区土壤碳含量变化的主要影响因素（P<0.05）。在黄土高原植被恢复过程中应充分考虑地形因子和土壤理化性质的影响。本研究结果可为正确评估人工林土壤碳储量及其生态效益提供基础数据和科学参考。  相似文献   

7.
免耕对华北地区潮土碳库特征的影响   总被引：1，自引：0，他引：1  
以实施7年的中国科学院禹城综合试验站冬小麦-夏玉米轮作免耕长期定位试验场为对象,系统研究免耕条件下土壤总碳(TC)、有机碳(SOC)、无机碳(SIC)的变化,为进一步评价免耕措施对华北地区潮土碳库的影响提供数据支持。研究设置免耕秸秆覆盖(NTRC)、免耕施用有机肥(NTRR)、常规耕作(CT)3种处理,分析表层(0-20cm)及深层(20-60cm)土壤TC、SOC及SIC的变化特征和影响因素。主要结果为:NTRC和NTRR能够增加0-20cm土层TC含量及储量,但降低20-60cm土层TC含量及储量,0-60cm总碳储量表现为NTRC>CT>NTRR;与CT相比,NTRC能够显著增加0-20cm而降低20-60cm土层SOC含量及储量,NTRR增加了0-5cm土层SOC含量及储量,在5-60cm则呈降低趋势,0-60cm土层SOC储量表现为CT>NTRC>NTRR;NTRC增加了0-60cm土层SIC储量,而NTRR则影响较小。TC与SOC呈显著正相关(P<0.05),而与SIC呈显著负相关(P<0.05),说明总碳的变化趋势与SOC一致,与SIC相反。  相似文献   

8.

Purpose

The objectives of the study were (1) to quantify the long-term effects of nitrogen-phosphorus fertilizer (NP) and a combination of nitrogen-phosphorus with organic manure (NPM) on total soil organic carbon (SOC) and total soil inorganic carbon (SIC), (2) to identify the changes of SOC and SIC in soil particle-size fractions, and (3) to investigate the relationship between SOC and SIC.

Materials and methods

Two long-term field experiments (sites A and B) were performed in 1984 (site A) and 1979 (site B) in the North China Plain. The soil samples were collected in 2006 and separated for clay, silt and sand size particle fractions and then determined for SOC and SIC.

Results and discussion

The long-term fertilization significantly increased SOC in 0–20 cm soil layer by 9–68% but significantly decreased or had no effect on SIC. In total, soil carbon storage was little affected by NP, but significantly increased by NPM application (p < 0.05). Fertilization affected both SOC and SIC in sand- and silt-sized particles but not in clay-size fraction. Both NP and NPM increased SOC in sand- and silt-sized particles by 8.7–123.9% in the 0–20 cm layer but decreased SIC up to 80.4% in the 40–60 cm layer. The SOC concentration in the particle-size fractions was negatively correlated with SIC concentration, which may imply an antagonistic interaction between organic and inorganic carbon levels.

Conclusions

These results illustrate the importance of soil inorganic carbon pool in evaluating soil total carbon pool in semi-arid farmlands. Previous assessments of the effects of fertilizers on the soil carbon pool, using only SOC determinations, require re-evaluation with the inclusion of SIC determinations.
  相似文献   

9.
Abstract

An anaerobic incubation experiment was conducted to investigate methane (CH4) production potential in soil samples collected from a paddy field after exposure to free-air CO2 enrichment (FACE). The FACE experiment with two CO2 levels, ambient and ambient + 200 p.p.m.v CO2 during the rice growing season, was conducted at Shizukuishi, Iwate Prefecture, Japan. The soil was a wet Andosol. Soil samples were taken from the surface (0–1 cm) and the sub-surface (1–10 cm) soil layers 2 months after rice harvest. Sub-samples of the fresh soils were put into glass bottles and submerged under N2 gas headspace during the incubation. The results showed that, prior to incubation, the contents of total C and dissolved organic C (DOC) were significantly greater in FACE soil than ambient soil. During the incubation, CH4 production potential was approximately 2–4-fold higher in FACE soil than ambient soil and approximately 500–1,000-fold greater in surface soil than sub-surface soil. In general, the FACE soil contained more DOC than ambient soil, particularly in the surface soil layer. These findings suggest that FACE treatment exerted long-term positive effects on CH4 production and increased organic C content in this paddy soil, particularly in the surface soil layer.  相似文献   

10.
More than 50% of global soil organic carbon stocks are stored below 20 cm of soil depth capable of massively altering global C cycle and climate. However, subsoil C dynamics are largely overlooked implicitly assuming that surface and subsoil C dynamics are similar. Here, we compared the soil C dynamics in surface and subsurface soil layers in response to nitrogen and maize leaf litter additions. Soils, sampled from 0 to 5, 15 to 35, 35 to 55 and 55 to 75 cm depths, were incubated at 25°C after adding litter, nitrogen (NH4NO3) or litter plus nitrogen. Soil respiration (C mineralization) was measured throughout the incubation period. Litter addition significantly increased C mineralization in all the soil layers. However, the soil CO2 release relative to control was more than twofold higher in 15–35 and 35–55 cm soil layers than the surface layer. Nitrogen additions significantly decreased C mineralization in 0–15 cm soil, increased in 35–55 cm and had minimal effects in the 15–35 and 55–75 cm layers. Different soil C dynamics in surface and subsurface soil layers found in our study contradict the general assumption that soil C dynamics may be treated similarly along different soil depths.  相似文献   

11.
Icelandic soils develop in a dynamic environment affected by both natural processes and anthropogenic impacts. We present an extensive investigation of soil mineralogy and pedogenesis in a disturbed (i.e., by solifluction) pedon under such conditions. The study focuses on two distinct tephra layers, a rhyolitic tephra from the Öræfajökull eruption in 1362 CE (Ö1362) and a basaltic Veiðivötn tephra from 1477 CE (V1477). Both tephra layers form an important parent material in the study area south of Vatnajökull, Iceland. The Andosol developed from tephra and aeolian material, rich in volcanic glass. The pH (H2O) values were between 5.5 and 6.6 and clay mineralogy displayed a predominance of allophanic material in both soil and tephra. The pedon can be seen in its early stage of chemical weathering and soil development. Despite the overall predominance of non- and poorly-crystalline short-range order secondary materials and Fe (hydr)oxides in the clay-size fraction, we found indication of smectite. High exchangeable Ca2+ and Mg2+ concentrations reflect enhanced aeolian input of volcanic material, while elevated exchangeable-Na+ concentrations are most likely caused by the oceanic composition of precipitation. The impact of erosion and aeolian processes on pedogenesis seemed to be higher between the deposition of Ö1362 and V1477, than in the soils above. Both, soil and tephra layers appeared disturbed by erosion–deposition processes over time. Characterised by a significantly coarser particle size composition, low soil organic carbon (SOC) content, and a more diverse mineralogy, a distinct fluvial sediment layer at 10–30 cm depth appeared sharply contrasting to the other soil layers in the profile. This possibly reflects the diverse composition of glaciofluvial material from a landslide originating from a Kvíárjökull moraine in the north. Changed weathering patterns and properties in the soils above the Ö1362 tephra indicated soil degradation following the deposition of the rhyolitic tephra.  相似文献   

12.

Purpose

Algae play an important role in degraded areas during the initial stages of soil formation by improving its physico-chemical properties, reducing the erosion of soil, and thus favoring the settlement of vascular plants. This study investigates the characters of soil algal communities on copper tailing dumps and discusses the contribution of soil algae to the primary succession progress of young mine tailings ecosystems.

Materials and methods

Five representative potential successional series (bare land, algae crust, mixed algal–moss crust, moss crust, and vegetated site) on copper tailing dumps and a nearby reference site were selected. The soil algae were identified using growth slide method, dilution plate method, and by direct microscopic observation of the soil suspensions. All experiments were carried in an incubation chamber at a temperature of 25 °C and with a 16 h/8 h light–dark cycle at a light intensity of 3,000 lux.

Results and discussion

A total of 120 algal species were recorded. Cyanophyta (blue-green algae) were the most diverse taxonomic group, followed by Bacillariophyta (diatoms) and Chlorophyta (green algae), although diatoms were absolutely absent in bare sites. Diversity of soil algae was highest in vegetated site, whereas it was lowest in bare sites. Total algal abundance ranged between 0.15?×?103 cells/g to 46.8?×?103 cells/g dry soil, with the lowest abundance in the youngest site and the highest abundance in the mixed algal–moss crust site. Correlation analysis showed that the growth of soil algae was inhibited by high Cu, Zn, and Fe concentrations and low nutrient content and that the green algae were more sensitive to nutrient content than blue-green algae.

Conclusions

Our results suggest that blue-green algae were most diverse, followed by diatoms and green algae. Species and abundance of soil algae in the tailings increased with the early succession process because of the decrease in heavy metal content and the improvement of nutrient conditions. The growth of soil algae created conditions for the settlement and growth of higher plants, but the appearance of moss and vascular plants inhibited the growth of soil algae.  相似文献   

13.
Quantification of soil organic carbon (SOC) is an important element in the assessment of the carbon sequestration potential of soils in tree-based intercropping (TBI) systems. The organic carbon (OC) concentrations of soils in TBI systems often differ from those in conventional agricultural systems due to the additional C inputs from litter fall and roots. However, the presence of soil inorganic carbon (SIC) can confound the measurements of SOC. This study compared three methods of measuring SOC: (i) measurement of the total soil C (TC) in one subsample and, after treatment in a muffle furnace (575 °C) for 24 h, measurement of SIC in another subsample; (ii) SOC measured after fumigation with 12 M hydrochloric acid (HCl) to remove SIC; and (iii) SOC measured after digestion with 0.73 M H2SO3 to remove SIC. The TC, SOC, and SIC concentrations were determined by combustion. A correction factor was applied to express SIC and SOC concentrations on an original, untreated soil basis. Measurement of SOC by the muffle furnace method resulted in the greatest SOC concentrations for Populus spp. (hybrid poplar) for samples from two of the three depths (0–10 and 20–40 cm). Measurement of SOC by the HCl fumigation and H2SO3 digestion methods were highly correlated, suggesting complete removal of SIC with minimal oxidation of SOC. These results have implications for the method of measuring SOC in calcareous soils under coniferous and deciduous tree species to a depth of 40 cm.  相似文献   

14.
Soil microorganisms play an important role in recycling and transformation of nutrients. Soil microbiological parameters and microbial biomass carbon (MBC) have been suggested as possible indicators of soil quality. Soil microorganisms and MBC in different continuous cropping soils were investigated. Results showed that bacterial population was the highest, followed by actinomycetes, and fungi were the lowest at 0–30 cm soil depth. The amount of soil microorganisms decreased with increasing soil depth (0–10 > 10–20 > 20–30 cm). Soil microbial ratios at different depths proved to be responsive to time (year) variations in continuous monocropping tomato, except those at 0–10 to 10–20 cm depth for fungi and 10–20 to 20–30 cm depth for bacteria. Soil MBC for 12 years of continuous cropping was significantly lower than those for 5, 8, and 10 years (P < 0.05). Continuous cropping years, soil depth, and the interaction of these two parameters significantly influenced soil fungal, bacterial, and actinomycetes populations and MBC. Bacterial population at the 0–10 cm soil layer was a sensitive indicator of continuous cropping of tomato. Soil fungal count increased with increasing monocropping time within 5–8 years.  相似文献   

15.
Abstract

The accident at Fukushima Dai-Ichi Nuclear Power Station (NPS) extensively contaminated the agricultural land in the Tohoku region of Japan with radioactive cesium [sum of cesium-134 (134Cs) and cesium-137 (137Cs)]. We evaluated the status of radioactive cesium (Cs) contamination in soil and plants at the Field Science Center of Tohoku University, northern Miyagi prefecture, 150 km north of the NPS. In seven pastures with different management, we examined: (1) the distribution of radioactive Cs in soil, (2) the concentration of radioactive Cs in various herbaceous plant species and (3) the change in radioactive Cs content of plants as they matured. We collected samples of litter, root mat layer (root mat soil and plant roots), and subsurface soil (0–5 cm beneath the root mat) at two to three locations in each pasture in December 2011 and May 2012. The aboveground parts of herbaceous plants (four grasses, two legumes, and one forb species) were collected from May 9 to June 20, 2012, at 14-d intervals, from one to five fixed sampling locations in each pasture. The distribution of radioactive Cs in soil differed among pastures to some degree: a large proportion of radioactive Cs was distributed in the root mat layer. Pasture management greatly influenced the radioactive Cs content of herbaceous plants (p < 0.001); plant species had less influence. Radioactive Cs content was highest (> 3 kBq kg?1 dry weight) on May 9 and significantly decreased with maturity (p < 0.001) for most of the pastures, whereas it remained low (0.04–0.18 kBq kg?1 dry weight) throughout the measurement period in the pasture where composted cattle manure was applied. The soil-to-plant transfer factor was negatively correlated to pH(H2O) (R2 = 0.783, p < 0.001) and exchangeable K content (R2 = 0.971, p < 0.001) of root mat soils, which suggests that surface application of composted cattle manure reduces plant uptake of radioactive Cs by increasing the exchangeable K content of the soil. The radioactive Cs content of plants decreased with plant maturity; its degree of decrease (May 9 to June 6) was smaller in legumes (80.6%) than grasses (55.5%) and the forb (58.6%). Radioactive Cs content decreased with plant maturity; also, the proportion remaining in the aboveground plant was higher in legumes (80.6%) than grasses (55.5%) and the forb (58.6%).  相似文献   

16.
In the present study, artificial neural networks (ANNs) were employed to develop models to predict soil organic carbon density (SOCD) at different depths of soil layers. Selected environmental variables such as vegetation indices, soil particle size distribution, land use type, besides primary and secondary terrain attributes were considered as the input variables. According to the results, the ANN models explained 77% and 72% of the variability in SOCD at soil layer depths of 0–20 cm and 20–40 cm, respectively, at the site studied. Sensitivity analyses showed that the most considerable positive contribution of variables for predicting SOCD included the land use type, normalized difference vegetation index (NDVI) > normalized difference water index (NDWI) > silt > clay > elevation in the 0–20 cm soil layer. On the other hand, for the 20–40 cm soil layer, the land use type following NDVI > NDWI > clay > silt were identified as the most powerful predictive factors. In the Deylaman region, in both soil layers, sand had a considerable negative effect on SOCD and most of the terrain attributes had no significant impact on the SOCD prediction. Therefore, these results provide valuable information for sustainable management and decision-making on a landscape scale for governors and other users.  相似文献   

17.
Plastic film mulching has commonly been used for adaptation to water scarcity and for increasing agricultural productivity on the semiarid Loess Plateau of China. However, the effect of plastic film mulching on cropland soil water and thermal regimes on the semiarid Loess Plateau of China is not well understood. This study simultaneously monitored the dynamics of the soil water content and the soil temperature with high resolution in a ridge cultivation system with plastic film mulching (RS) and a flat cultivation system without plastic film mulching (FS) during the maize (Zea mays L.)-growing season. We found that, in general, the soil temperature and soil water content were significantly different among the ridge under RS (RS-ridge), the furrow under RS (RS-furrow) and FS throughout the maize-growing season (P < 0.05). Plastic film mulching increased the near-surface soil temperature by approximately 1°C throughout the study period. RS significantly increased the soil water content during the dry period (May to June), especially within the middle soil layer (30–60 cm), compared to FS. The lowest monthly average soil water content was found at a depth of 30–60 cm layer in FS during the dry period (May and June). The water depletion was found within deeper (100–160 cm) soil layers in May but the water storage in the same layer of FS in June increased although it was the dry period, which differed from RS. The RS practices showed a longer period of water supply from the deeper soil layer (100–160 cm) in May and June for meeting maize water demands during the early growing stage rather than in only May for FS. During June (dry period), the water storage at a depth of 0–60 cm was greater in RS than in FS, and the reverse was true at a depth of 60–160 cm. The results indicate that the dry soil layer at a depth of 30–60 cm formed during June in FS likely reduced water movement from deeper layers to the topsoil layer, and hence constrained the availability of surface soil water for meeting maize water requirements during the early growing stage (dry period). Our study suggests that RS tends to significantly increase surface soil water availability by restraining the formation of a dry soil layer during the early maize-growth stage primarily under dry conditions, and thus enhances maize productivity in the semiarid Loess Plateau of China.  相似文献   

18.
Biopores are hotspots of nutrient mobilisation and shortcuts for carbon (C) into subsoils. C processing relies on microbial community composition, which remains unexplored in subsoil biopores. Phospholipid fatty acids (PLFAs; markers for living microbial groups) and amino sugars (microbial necromass markers) were extracted from two subsoil depths (45–75 cm ; 75–105 cm) and three biopore types: (I) drilosphere of Lumbricus terrestris L., (II) 2-year-old root biopores and (III) 1.5-year-old root biopores plus six 6 months of L. terrestris activities. Biopore C contents were at least 2.5 times higher than in bulk soil, causing 26–35 times higher Σ PLFAs g-1 soil. The highest Σ PLFAs were found in both earthworm biopore types; thus, the highest soil organic matter and nutrient turnover were assumed. Σ PLFAs was 33% lower in root pores than in earthworm pores. The treatment affected the microbial community composition more strongly than soil depth, hinting to similar C quality in biopores: Gram-positives including actinobacteria were more abundant in root pores than in earthworm pores, probably due to lower C bioavailability in the former. Both earthworm pore types featured fresh litter input, promoting growth of Gram-negatives and fungi. Earthworms in root pores shifted the composition of the microbial community heavily and turned root pores into earthworm pores within 6 months. Only recent communities were affected and they reflect a strong heterogeneity of microbial activity and functions in subsoil hotspots, whereas biopore-specific necromass accumulation from different microbial groups was absent.  相似文献   

19.
In Indian Punjab, rice–wheat is a dominant cropping system in four agro‐ecosystems, namely undulating subregion (zone 1), Piedmont alluvial plains (zone 2), central alluvial plains (zone 3), and southwestern alluvial plains (zone 4), varying in rainfall and temperature. Static and temporal variabilities in soil physical and chemical properties prevail because of alluvial parent material, management/tillage operations, and duration of rice–wheat rotation. A detailed survey was undertaken to study the long‐term effect of rice–wheat rotation on soil physical (soil separates, bulk density, modulus of rupture, saturated and unsaturated hydraulic conductivities, soil water content, and suction relations) and chemical (organic carbon, pH, electrical conductivity) properties of different textured soils (sandy clay loam, loam, clay loam, and silty clay loam) in these four zones of Punjab. Soil samples (of 0‐ to 30‐cm depth) from 45 sites were collected during 2006 and were analyzed for physical and chemical properties. The results showed that sand content and pH increased whereas silt and organic carbon decreased significantly from zones 1 to 4. Compared to other textures, significantly greater organic carbon, modulus of rupture, and pH in silty clay loam; greater bulk density in clay loam, and greater saturated hydraulic conductivity in sandy clay loam were observed. Irrespective of zone and soil texture, in the subsurface soil, there was a hard pan at 15–22.5 cm deep, which had high soil bulk density, modulus of rupture, more silt and clay contents (by 3–5%) and less organic carbon and hydraulic conductivity than the surface (0–15 cm) layer. These properties deteriorated with fineness of the soil texture and less organic carbon content. Continuous rice–wheat cropping had a deleterious effect on many soil properties. Many of these soils would benefit from the addition of organic matter, and crop yields may also be affected by the distinct hardpan that exists between 15 and 22.5 cm deep.  相似文献   

20.
With diminishing world reserves of phosphorus (P) deposits and rising fertilizer prices, it is important to find alternate sources of P for crops. The aim of this research was to evaluate the effect of four different composts C1 (animal manure and straw), C2 (garden waste), C3 (wood chips and bark), and C4 (kitchen waste) on soil P pools and P uptake by wheat on 14, 28, and 72 days after compost application. The composts were applied as a 2.5 cm thick layer on the soil surface. During sampling, only the soil underlying compost was sampled. Soil pH and total organic carbon were not affected by the amendments. Soil respiration was significantly higher in compost-amended soils compared with the unamended soil except with C4 on day 72. Addition of composts increased plant growth, and P uptake being highest on day 72 with C1 and C4. With little effect on available P concentration on day 14, there was a conversion of organic P into inorganic P in the compost treatments suggesting net mineralization of organic P on day 28. On day 72, the concentrations of the less labile P forms were higher in the compost treatments compared with the unamended suggesting precipitation and fixation as well as synthesis of organic P. This study showed that mulching with composts having high available and total P concentrations can provide plants with P and also increase soil P concentrations which could reduce the fertilizer requirement for the following crop.  相似文献   

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