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1.
New non-tillage or reduced tillage agricultural practises are being increasingly adopted but generally result in higher soil compaction. Due to their recognised physical influence mainly through burrow creation, it is often claimed that earthworm activity could alleviate soil compaction in these systems. To put this assumption to the test, an experimental compaction event was carried out on one plot of arable land. The abundance and biomass of earthworms were evaluated in compacted (under wheel tracks) and non-compacted (between wheel tracks) zones, seven times over a two-year period. In addition, the functional consequences of earthworm activity, defined by burrow abundance assessed in 2D and 3D and water infiltration, were measured three times over the same period. The short-term (less than three months) effects of the compaction were clear: soil bulk density increased from 1.46 to 1.57 g cm−3, the abundance and biomass of earthworms were greatly reduced (−40% and −70% respectively) and the number and continuity of macroporosity were lower under wheel tracks at least until a depth of 30 cm. After these initial detrimental effects, we observed a rapid recovery of earthworm populations with no statistical difference between compacted and control zones more than three months after the compaction. However, the recovery of soil functional properties linked to earthworm activity, macroporosity and water infiltration, was much slower and took between 12 and 24 months. Despite these modifications, there were no significant changes in soil bulk density with time during the two-year period. This study demonstrates that earthworms are important actors in the regeneration of compacted soil. Although the complete regeneration of compacted soil by earthworms is a slow process, agricultural practises that promote earthworm density and activity should be encouraged in reduced or minimum tillage systems.  相似文献   

2.
One of the key issues to increase soil productivity in the Sahel is to ensure water infiltration and storage in the soil. We hypothesised that reducing tillage from annual to biennial ploughing and the use of organic matter, like compost, would better sustain soil hydraulic properties. The study had the objective to propose sustainable soil fertility management techniques in the cotton–maize cropping systems. The effects of reduced tillage (RT) and annual ploughing (AP) combined with compost application (Co) on soil infiltration parameters were assessed on two soil types. Topsoil mean saturated hydraulic conductivities (Ks) were between 9 and 48 mm h−1 in the Luvisol, while in the Lixisol they were between 18 and 275 mm h−1. In the two soil types compost additions with reduced tillage or with annual ploughing had the largest effect on Ks. Soil hydraulic behaviour was in reasonable agreement with soil pore size distribution (mean values varied from 19.5 to 237 μm) modified by tillage frequency and organo-mineral fertilization. Already the first 3 years of this study showed that use of organic matter, improved soil infiltration characteristics when annual ploughing was used. Also biennial ploughing showed promising results and may be a useful strategy for smallholders to manage these soils.  相似文献   

3.
Severe treading damage to soils often occurs when cattle and sheep graze standing forage crops during winter. Soil recovery is a long process that may take several months if not years. Noninversion tillage can speed up the recovery process by improving drainage and air diffusion. This research assessed the ongoing benefit of noninversion tillage for improving soil structure relative to non‐tillage. This assessment was made following a land‐use transition from winter forage cropping to re‐establishment of seasonal pasture that was rotationally grazed by cattle or sheep. Prior to commencement of this study, the research site had poor soil structure due to four consecutive years of cattle and sheep grazing of winter forage crops [macroporosity (0–100 mm) <0.075 and 0.113 m3/m3 under cattle and sheep, respectively]. Tillage was effective in increasing soil macroporosity to ca. 0.175 m3/m3 under both grazing classes, which was significantly higher than nontilled soils (ca. 0.140 m3/m3, 0–100 mm depth). Improvements gained from tillage generally did not persist longer than 18 months. Average annual pasture production in tilled plots was 22.1 and 20.9 tons of dry matter per hectare (t DM/ha) for respective cattle‐ and sheep‐grazed plots, while in the nontilled plots, it was 19.1 and 18.6 t DM/ha, respectively. Results indicate noninversion tillage can provide an immediate increase in the porosity of compacted soils and improve pasture growth. However, processes involved in the formation of resilient soil aggregates are curtailed if subsequent grazing events coincide with high moisture content that causes recompaction.  相似文献   

4.
In laboratory experiments, earthworms are often observed to burrow through compacted soil layers, leading to the general assumption that these animals play a significant role in regenerating compacted soils in agricultural plots. To demonstrate this role under field conditions, the abundance of earthworm macropores inside compacted zones was estimated on plots under reduced (RT) or conventional tillage (CT). Then, different types of compacted zones typically found in CT (plough pan and compacted clods) and RT plots (compacted volume under wheel tracks) were experimentally simulated in wooden boxes, buried in the field and inoculated with different earthworm species. After 6 weeks of incubation, the number of macropores inside the compacted zones was examined. Field observations showed that approximately 10% and 30% of the compacted zones were colonised by at least one macropore in CT and RT plots, respectively. A significantly greater number of anecics was found in RT plots, but we could not conclude that this ecological type of earthworm plays a more major role in the regeneration process in these plots since there were fewer compacted zones and these covered a smaller area in CT. The semi-field experiment provided evidence that earthworm-mediated regeneration of compacted zones is possible and its nature varies between ecological types of earthworm. Lumbricus terrestris, which makes individual burrows that are vertical and deep, was the main species to cross through the plough pan. The other three earthworm species (Aporrectodea giardi, A. caliginosa and A. rosea) did burrow inside the other types of compacted zones (“wheel tracks” and “compacted clods”). In every case, however, macropore density was far greater in non-compacted zones, illustrating that avoidance of compacted soil by earthworms is important and should be taken into account when extrapolating results from laboratory studies.  相似文献   

5.
Earthworm burrows contribute to soil macroporosity and support diverse microbial communities. It is not well known how fluctuations in soil temperature and moisture affect the burrowing activities of earthworms. The objective of this experiment was to evaluate the maximum depth and length of burrows created by the endogeic earthworm Aporrectodea caliginosa (Savigny) and the anecic earthworm Lumbricus terrestris L. for a range of temperatures (5–20 °C) and soil water potentials (−5 and −11 kPa). The laboratory microcosm was a plexiglass chamber (45 cm high, 45 cm wide) containing 0.14 m2 of pre-moistened soil and litter, designed to house a single earthworm for 7 days. Earthworm mass, surface casting and burrowing activities were affected significantly by soil temperature, moisture and the temperature×moisture interaction. Burrow length and maximum burrow depth increased with increasing temperature, but there was less burrowing in wetter soil (−5 kPa) than drier soil (−11 kPa). Weight gain and surface casting, however, were greater in soil at −5 kPa than −11 kPa. Our results suggest more intensive feeding and limited burrowing in wetter soil than drier soil. Earthworms inhabiting the non-compacted, drier soil may have pushed aside particles without ingesting them to create burrows. The result was that earthworms explored a larger volume of soil, deeper in the chamber, when the soil was drier. How these burrowing activities may affect the community structure and activity of soil microorganisms and microfauna in the drilosphere remains to be determined.  相似文献   

6.
Farmers within the Inland Pacific Northwest are gradually transitioning to direct seed (DS) practices that reduce soil disturbance and increase surface residue compared to conventional tillage (CT). Despite this transition the impacts of DS practices on soil properties and fauna in commercial fields has been little studied in the region. During the spring and summer of 2002 and 2003 we compared soil organic carbon (SOC), total nitrogen (TN), pH, and earthworm and cocoon densities in CT and DS fields planted to either spring wheat or pea in the Palouse region of northern Idaho. In 2002 mean SOC within the 0–10-cm depth was greater in DS fields (2.05%) than at the same depth in CT fields (1.79%), however SOC within the 30–40-cm depth was lower under DS compared to CT. Mean soil pH within the 0–10-cm depth was 5.35 under DS and 5.61 under CT indicating that pH stratification can occur when tillage is reduced. Tillage effects on SOC, TN, and pH were not found in 2003. Tillage also did not significantly influence earthworm densities, which averaged 39 individuals m−2 in 2002 and 57 individuals m−2 in 2003. Correlations were detected in 2003 DS fields between soil properties (SOC and TN) and earthworm and cocoon densities at depths above 30 cm while in 2002 correlations in DS fields occurred with cocoon density, but not with earthworm density. Direct seed management can increase near-surface SOC and TN concentrations compared to CT practices, however, SOC concentrations deeper in the soil appear to remain the same or possibly decrease. Higher SOC and TN near the soil surface, as found in DS fields, appear to promote greater earthworm densities, which may improve long-term soil productivity.  相似文献   

7.
Crop residues and reduced tillage become current tendency in modifying tillage due to better water management, organic and nutrient supply and increasing crop production. This study was carried out to quantify the effect of fodder radish mulching and different tillage systems in wheat production. In 2004–2006 the field trial was set up on Luvic Chernozems derived from loess. This experiment consisted of two factors: tillage system (conventional or reduced) and mulch (with or without). The air–water properties of soil with particular focus on macropore characteristics were investigated.The tillage system and mulch application significantly influenced physical properties of investigated soil. Reduced tillage, without mouldboard plough, increased the soil density with respect to conventional tillage. However, in the upper soil layer (0–10 cm) with mulch residues the bulk density decreased and reached the similar value as those obtained at conventional tillage (1.25 g cm−3). The macroporosity of soil with conventional tillage (14.79%) was significantly higher in comparison with reduced tillage (6.55%). The mulch of fodder radish added at reduced tillage increased the macroporosity in pore diameter range of 50–500 μm. These changes referred to all shape classes: regular, irregular and elongated pores. The lowest transmission pores content (0.078 cm3 cm−3) was noticed at the reduced tillage without mulch at the 0–10 cm layer. Due to lack of differences in storage pores the tillage and mulching had no effect on both AWC (available water content) and PWC (productive water content) values. The higher value of AWC was noticed in the upper soil layer (0.198 cm3 cm−3 in average), whereas in the 10–20 cm soil layer it was 0.186 cm3 cm−3. Similar relation was recorded in PWC values, 0.165 and 0.154 cm3 cm−3, respectively. The results obtained in physical properties of soil reflected in wheat yields. The yields obtained at reduced tillage system without mulch (5.54 t ha−1) were significant lower with respect to treatment when mulch applied (6.79 t ha−1). The mulch residues did not affect yields at conventional tillage (6.53 t ha−1 without mulch and 7.00 t ha−1 with mulch). The main conclusion is that the mulching can help to avoid yield reduction in wheat production when reduced tillage is used.  相似文献   

8.
The population abundance of free-living and plant-parasitic nematodes was investigated in a long-term rotation/tillage/stubble management experiment at Wagga Wagga Agricultural Institute, New South Wales (NSW), Australia. The treatments were a combination of two crop rotations: wheat (Triticum aestivum)–wheat and wheat–lupin (Lupinus angustifolius); two tillage systems: conventional cultivation (CC) and direct drill (DD); and two stubble management practices: stubble retention (SR) and stubble burnt (SB). Plots of one of the wheat–wheat treatments received urea at 100 kg N ha−1 during the cropping season. Soil samples from 0–5 and 5–10 cm depths were collected in September (maximum tillering), October (flowering) and December (after harvest), 2001, to analyse nematode abundance. Soil collected in September was also analysed for concentrations of total and labile C, and pH levels.Three nematode trophic groups, namely bacteria-feeders (primarily Rhabditidae), omnivores (primarily Dorylaimidae excluding plant-parasites and predators) and plant-parasites (Pratylenchus spp. and Paratylenchus spp.) were recorded in each soil sample. Of them, bacteria-feeders (53–99%, population range 933–2750 kg−1 soil) dominated in all soil samples. There was no difference in nematode abundance and community composition between the 0–5 cm and 5–10 cm layers of soil. The mean population of free-living and plant-parasitic nematodes varied significantly between the treatments in all sampling months. In most cases, total free-living nematode densities (Rhabditidae and Dorylaimidae) were significantly (P < 0.001) greater in wheat–lupin rotation than the wheat–wheat rotation irrespective of tillage and stubble management practices. In contrast, a greater population of plant-parasitic nematodes was recorded from plots with wheat–wheat than the wheat–lupin rotation. For treatments with wheat–wheat, total plant-parasitic nematode (Pratylenchus spp. and Paratylenchus spp.) densities were greater in plots without N-fertiliser (295–741 kg−1 soil) than the plots with N-fertiliser (14–158 kg−1 soil).Tillage practices had significant (P < 0.05) effects mostly on the population densities of plant-parasitic nematodes while stubble management had significant effects (P < 0.05) on free-living nematodes. However, interaction effects of tillage and stubble were significant (P < 0.01) for the population densities of free-living nematodes only. Population of Rhabditidae was significantly higher in conventional cultivated plots (7244 kg−1 soil) than the direct drilled (3981 kg−1 soil) plots under stubble retention. In contrast, plots with direct drill and stubble burnt had significantly higher populations of Dorylaimidae than the conventional cultivation with similar stubble management practice. No correlations between abundance of free-living nematodes, and concentration of total C and labile C in soil were observed in this study. These results showed that stubble retention contributed for enormous population density of free-living (beneficial) nematodes while conventional cultivation, irrespective of stubble management, contributed for suppressing plant-parasitic nematodes.  相似文献   

9.
A field experiment was conducted from 1983 to 1992 in Tsukuba, Japan to investigate the effects of tillage on soil conditions and crop growth in a light-colored Andosol. Three tillage methods (NT: no-tillage, RT: no-tillage for summer cropping and moldboard plowing for winter cropping, and CT: conventional rotary tillage to a depth of 15 cm) were employed in combination with crop residue application (+R, −R) and fused magnesium phosphate (FMP) fertilization (+P, −P). Under the combination of NT and +R, diurnal variation of soil temperature at a depth of 5 cm was smaller during the summer cropping season and soil temperature in the daytime was lower during the winter cropping season than under CT. Soil inorganic N concentration at a depth of 0–30 cm was +R > −R and NT > RT > CT. The early growth of summer crops was accelerated under NT in comparison with CT, and yields were higher under NT and RT in comparison with CT. On the other hand, winter crop yields were significantly reduced under NT, while they were still higher under RT in comparison with CT. Yields were higher with +R and +P application, respectively, and these effects were more pronounced in winter cropping. The positive effect of FMP fertilization was greater in combination with NT, and that of residue treatment was greater in combination with RT and NT than with CT. In conclusion, the best tillage practice for Andosols on the Kanto Plain is RT, i.e. a combination of NT for summer cropping and CT for winter cropping. The application of NT for winter cropping is not recommended, although the application of phosphate and crop residues could reduce the risk of yield reduction, because of improved soil nutrient status and moderation of diurnal soil temperature.  相似文献   

10.
Improved legume tree fallows have great potential to increase soil organic carbon (SOC), aggregate stability and soil infiltration rates during the fallowing phase. However, persistence of the residual effects of improved fallowing on SOC, aggregate stability and infiltration rates, under different tillage systems in Zimbabwe is not well documented. The relationships between SOC, aggregate stability and infiltration in fallow-maize rotation systems are also not well documented. We therefore evaluated effects of tillage on SOC, aggregate stability and infiltration rates of a kaolinitic sandy soil during the cropping phase of an improved fallow-maize rotation system. Plots that were under legume tree fallows (Sesbania sesban; Acacia angustissima), natural fallow (NF) and under continuous maize during the previous 2 years were divided into conventional tillage (CT) and no-till (NT) subplots soon after fallow termination, and maize was cropped in all plots during the following two seasons. Aggregate stability was investigated using water stable macroaggregation index (Ima), water dispersible clay (WDC) and using the mean weight diameter (MWD) after different wetting procedures. Infiltration rates were determined using simulated rainfall at intensity of 35 mm h−1 on 1 m2 plots. Soil organic carbon was significantly higher (P < 0.05) under fallows than continuous maize. For the 0–5 cm depth SOC was 11.0, 10.0, 9.4 and 6.6 g kg−1 for A. angustissima, S. sesban, NF and continuous maize, respectively, at fallow termination. After 2 years of cropping SOC was 8.0, 7.0, 6.1 and 5.9 g kg−1 under CT and 9.1, 9.0, 8.0 and 6.0 g kg−1 under NT for A. angustissima, S. sesban, NF and continuous maize, respectively. Aggregate stability was significantly greater (P < 0.05) under fallows than under continuous maize and also higher under NT than under CT. The macroaggregation index (Ima) for the 0–5 cm depth was 466, 416, 515 and 301 for A. angustissima, S. sesban, NF and continuous maize, respectively at fallow termination, decreasing to 385, 274, 286 and 255 under CT and 438, 300, 325 and 270 under NT, for A. angustissima, S. sesban, NF and continuous maize, respectively, after 2 years of cropping. Percent WDC was also significantly lower (P < 0.05) in fallows than in continuous maize, and for the 0–5 cm it was 11, 10, 8 and 17 for A. angustissima, S. sesban, NF and continuous maize, respectively at fallow termination. After 2 years of cropping WDC (%) was 12, 14, 15 and 17 under CT and 10, 12, 12 and 16 under NT for A. angustissima, S. sesban, NF and continuous maize, respectively. MWD also showed significantly higher (P < 0.05) aggregate stability in fallows than in continuous maize. Water infiltration rates were significantly greater under fallows than continuous maize but these declined significantly during the cropping phase in plots that had been fallowed. In October 2000, infiltration rates in the A. angustissima and NF plots were above 35 mm h−1 as no runoff was observed. Steady-state infiltration rates were 24 mm h−1 in S. sesban and 5 mm h−1 for continuous maize after 30 min of rainfall simulations. After 2 years of cropping infiltration rates remained above 35 mm h−1 in A. angustissima plots, but declined to 18 and 8 mm h−1 for NF, CT and NT respectively and 12 mm h−1 for S. sesban, CT and NT. It is concluded that legume tree fallows improved SOC, aggregate stability and infiltration rates, but these benefits accrued during fallowing decreased significantly after 2 years of cropping following the termination of fallows. The decrease in SOC and aggregate stability was higher under CT than NT. Coppicing fallows of A. angustissima were the best long-term fallow species when integrated with NT as improved soil physical properties were maintained beyond 2 years of post-fallow cropping.  相似文献   

11.
Conventional tillage creates soil physical conditions that may restrict earthworm movement and accelerate crop residue decomposition, thus reducing the food supply for earthworms. These negative impacts may be alleviated by retaining crop residues in agroecosystems. The objective of this study was to determine the effects of various tillage and crop residue management practices on earthworm populations in the field and earthworm growth under controlled conditions. Population assessments were conducted at two long-term (15+ years) experimental sites in Québec, Canada with three tillage systems: moldboard plow/disk harrow (CT), chisel plow or disk harrow (RT) and no tillage (NT), as well as two levels of crop residue inputs (high and low). Earthworm growth was assessed in intact soil cores from both sites. In the field, earthworm populations and biomass were greater with long-term NT than CT and RT practices, but not affected by crop residue management. Laboratory growth rates of Aporrectodea turgida (Eisen) in intact soil cores were affected by tillage and residue inputs, and were positively correlated with the soil organic C pool, suggesting that tillage and residue management practices that increase the soil organic C pool provide more organic substrates for earthworm growth. The highest earthworm growth rates were in soils from RT plots with high residue input, which differed from the response of earthworm populations to tillage and residue management treatments in the field. Our results suggest that tillage-induced disturbance probably has a greater impact than food availability on earthworm populations in cool, humid agroecosystems.  相似文献   

12.
A better understanding of tillage and stubble management effects on surface soil structure is vital for the development of effective soil conservation practices for the long-term. Relationships between aspects of soil structure and runoff/soil loss were investigated in 24 year old field experiment on an Oxic Paleustalf, in NSW, Australia. Two tillage/stubble management systems were compared, namely direct drilled/stubble retained (DD/SR) versus conventional tillage/stubble burnt (CC/SB). Tillage and stubble burning significantly increased bulk density and decreased the macro-aggregate stability, mean weight diameter (MWD), geometric mean diameter (GMD) and total porosity, particularly macroporosity (>60 μm). For the 0–5 cm layer, DD/SR had significantly higher water stability of macro-aggregates >2 mm than CC/SB (165 g/kg versus 78 g/kg), and the volume of pore space of diameter >60 μm at 0–5 cm depth was significantly greater (more than 11%) for DD/SR than for CC/SB. Under simulated rainfall (100 mm/h) and the removal of surface stubble, both runoff and soil loss were significantly higher under CC/SB compared to DD/SR. The infiltration rate at the end of the experiment under DD/SR was 3.7 times that of CC/SB (85 mm/h versus 23 mm/h). There were significant correlations between the proportion of soil particles >0.25 mm measured after wetting by rain and both final infiltration rate (P < 0.001) and soil loss (P < 0.001). It was concluded that 24 years of direct drilling and stubble retained practices significantly reduced runoff and soil erosion hazards, due to a fundamental change in soil structure, viz. higher soil aggregate stability and higher macroporosity of the surface soil.  相似文献   

13.
The extreme climate of the northern Great Plains of North America requires cropping systems to possess a resilient soil resource in order to be sustainable. This paper summarizes the interactive effects of tillage, crop sequence, and cropping intensity on soil quality indicators for two long-term cropping system experiments in the northern Great Plains. The experiments, located in central North Dakota, were established in 1984 and 1993 on a Wilton silt loam (FAO: Calcic Siltic Chernozem; USDA1: fine-silty, mixed, superactive frigid Pachic Haplustoll). Soil physical, chemical, and biological properties considered as indicators of soil quality were evaluated in spring 2001 in both experiments at depths of 0–7.5, 7.5–15, and 15–30 cm. Management effects on soil properties were largely limited to the surface 7.5 cm in both experiments. For the experiment established in 1984, differences in soil condition between a continuous crop, no-till system and a crop–fallow, conventional tillage system were substantial. Within the surface 7.5 cm, the continuous crop, no-till system possessed significantly more soil organic C (by 7.28 Mg ha−1), particulate organic matter C (POM-C) (by 4.98 Mg ha−1), potentially mineralizable N (PMN) (by 32.4 kg ha−1), and microbial biomass C (by 586 kg ha−1), as well as greater aggregate stability (by 33.4%) and faster infiltration rates (by 55.6 cm h−1) relative to the crop–fallow, conventional tillage system. Thus, soil from the continuous crop, no-till system was improved with respect to its ability to provide a source for plant nutrients, withstand erosion, and facilitate water transfer. Soil properties were affected less by management practices in the experiment established in 1993, although organic matter related properties tended to be greater under continuous cropping or minimum tillage than crop sequences with fallow or no-till. In particular, PMN and microbial biomass C were greatest in continuous spring wheat (with residue removed) (22.5 kg ha−1 for PMN; 792 kg ha−1 for microbial biomass C) as compared with sequences with fallow (SW–S–F and SW–F) (Average=15.9 kg ha−1 for PMN; 577 kg ha−1 for microbial biomass C). Results from both experiments confirm that farmers in the northern Great Plains of North America can improve soil quality and agricultural sustainability by adopting production systems that employ intensive cropping practices with reduced tillage management.  相似文献   

14.
Endogeic and juvenile anecic earthworm abundance was measured in soil samples and anecic populations were studied by counting midden numbers at the sites of two long-term cropping systems trials in South-central Wisconsin. The three grain and three forage systems at each site were designed to reflect a range of Midwestern USA production strategies. The primary objectives of this work were to determine if the abundance of endogeic or anecic earthworms varied among cropping systems or crop phases within a cropping system and were there specific management practices that impacted endogeic or anecic earthworm numbers. The earthworms present in the surface soil were: Aporrectodea tuberculata (Eisen), A. caliginosa (Savigny), A. trapezoides (Dugés); and juvenile Lumbricus terrestris (L.). True endogeic abundance was greatest in rotationally grazed pasture [188 m?2 at Arlington (ARL) and 299 m?2 at Elkhorn (ELK)], and smallest in conventional continuous corn (27 m?2 at ARL and 32 m?2 at ELK). The only type of anecic earthworm found was L. terrestris L. There was an average of 1.2 middens per adult anecic earthworm and the population of anecics was greatest in the no-till cash grain system (28 middens m?2 at ARL, 18 m?2 at ELK) and smallest in the conventional continuous corn system (3 middens m?2 at ARL, 1 m?2 at ELK). Earthworm numbers in individual crop phases within a cropping system were too variable from year-to-year to recommend using a single phase to characterize a whole cropping system. Indices for five management factors (tillage, manure inputs, solid stand, pesticide use, and crop diversity) were examined, and manure use and tillage were the most important impacting earthworm numbers across the range of cropping systems. Manure use was the most important management factor affecting endogeic earthworm numbers; but no-tillage was the most important for the juvenile and adult anecic groups and had a significantly positive influence on endogeic earthworm counts as well. The pesticides used, which were among the most commonly applied pesticides in the Midwestern USA, and increasing crop diversity did not have a significant effect on either the endogeic or anecic earthworm groups in this study. Consequently, designing cropping systems that reduce tillage and include manure with less regard to omitting pesticides or increasing crop diversity should enhance earthworm populations and probably improve sustainability.  相似文献   

15.
Grazing of cover crops in grain cropping systems can increase economic return and diversify agricultural production systems, but the environmental consequences of this intensified management have not been well documented, especially under different tillage systems. We conducted a multiple-year investigation of how cover crop management (grazed and ungrazed) and tillage system [conventional (CT; initial moldboard plowing and thereafter disk tillage) and no tillage (NT)] affected soil physical properties (bulk density, aggregation, infiltration, and penetration resistance) on a Typic Kanhapludult in Georgia. Responses were determined in two cropping systems: summer grain/winter cover crop and winter grain/summer cover crop. Soil bulk density was reduced (P = 0.02) with CT compared with NT to a depth of 30 cm at the end of 0.5 year, but only to a depth of 12 cm at the end of 2, 2.5, and 4.5 years. Grazing of cover crops had little effect on soil bulk density, except eventually with 4.5 years of management. Water-stable macroaggregation was reduced (P ≤ 0.01) with CT compared with NT to a depth of 12 cm at all sampling times during the first 2.5 years of evaluation. Stability of macroaggregates in water was unaffected by grazing of cover crops in both tillage systems. Across 7 sampling events during the first 4 years, there was a tendency (P = 0.07) for water infiltration rate to be lower with grazing of cover crops (5.6 mm min−1) than when ungrazed (6.9 mm min−1), irrespective of tillage system. Across 10 sampling events, soil penetration resistance was greater under NT than under CT at a depth of 0–10 cm (P = 0.001) and the difference was greater in ungrazed than in grazed systems (P = 0.06). Biannual CT operations may have alleviated any surface degradation with animal traffic, but the initially high level of soil organic matter following long-term pasture and conversion to cropland with NT may have buffered the soil from any detrimental effects of animal traffic. Overall, the introduction of cattle to consume the high-quality cover crop forage did not cause substantial damage to the soil.  相似文献   

16.
Integrated crop–livestock management systems (ICLS) have been increasingly recommended in Brazilian agroecosystems. However, knowledge of their effect on soil organic carbon (SOC) and total nitrogen (TN) concentrations and stocks is still limited. The study was undertaken to evaluate the effects of ICLS under two tillage and fertilization regimes on SOC and TN concentrations and stocks in the 0–30 cm soil layer, in comparison with continuous crops or pasture. The following soil management systems were studied: continuous pasture; continuous crop; 4 years’ crop followed by 4 years’ pasture and vice-versa. The adjacent native Cerrado area was used as a control. Under the rotation and continuous crop systems there were two levels of soil tillage (conventional and no-tillage) and fertility (maintenance and corrective fertility). The stock calculations were done using the equivalent soil mass approach. The land use systems had a significant effect on the concentrations of SOC and TN in the soil, but no effect was observed for the soil tillage and fertilizer regimes. For these two latter, some significant discrepancies appeared in the distribution of SOC and TN concentrations in the 0–30 cm layer. Carbon storage was 60.87 Mg ha−1 under Cerrado, and ranged from 52.21 Mg ha−1 under the ICLS rotation to 59.89 Mg ha−1 with continuous cropping. The decrease in SOC stocks was approximately 8.5 and 7.5 Mg ha−1, or 14 and 12%, for continuous pasture and ICLS respectively. No-tillage for 10 years after the conversion of conventional tillage to no-tillage under the continuous crop system, and 13 years of conventional tillage in continuous cropping did not result in significant changes in SOC stocks. The SOC and TN stocks in surface layers, using the equivalent soil mass approach rather than the equivalent depth, stress the differences induced by the calculation method. As soil compaction is the principal feature of variability of stocks determinations, the thickness should be avoid in these types of studies.  相似文献   

17.
Earthworm growth is affected by fluctuations in soil temperature and moisture and hence, may be used as an indicator of earthworm activity under field conditions. There is no standard methodology for measuring earthworm growth and results obtained in the laboratory with a variety of food sources, soil quantities and container shapes cannot easily be compared or used to estimate earthworm growth in the field. The objective of this experiment was to determine growth rates of the endogeic earthworm Aporrectodea caliginosa (Savigny) over a range of temperatures (5–20 °C) and soil water potentials (−5 to−54 kPa) in disturbed and undisturbed soil columns in the laboratory. We used PVC cores (6 cm diameter, 15 cm height) containing undisturbed and disturbed soil, and 1 l cylindrical pots (11 cm diameter, 14 cm height) with disturbed soil. All containers contained about 500 g of moist soil. The growth rates of juvenile A. caliginosa were determined after 14–28 days. The instantaneous growth rate (IGR) was affected significantly by soil moisture, temperature, and the temperature×moisture interaction, ranging from −0.092 to 0.037 d−1. Optimum growth conditions for A. caliginosa were at 20 °C and −5 kPa water potential, and they lost weight when the soil water potential was −54 kPa for all temperatures and also when the temperature was 5 °C for all water potentials. Growth rates were significantly greater in pots than in cores, but the growth rates of earthworms in cores with undisturbed or disturbed soil did not differ significantly. The feeding and burrowing habits of earthworms should be considered when choosing the container for growth experiments in order to improve our ability to extrapolate earthworm growth rates from the laboratory to the field.  相似文献   

18.
Earthworm activity produces changes at different scales of soil porosity, including the mesoporosity (between 1.000 and 30 μm eq. dia.) where both water retention and near-saturated infiltration take place. At this scale, the structural changes are poorly described in temperate agricultural systems, so we do not yet fully understand how these changes occur. The present study was conducted to determine the relationships between the morphology of the mesopores, which is mainly affected by earthworm activity, and the hydrodynamic behaviour (near-saturated infiltration) of topsoil under different agricultural managements inducing a large range of earthworm populations.Investigations were carried out at the soil surface in three fields under different management practices giving rise to three different earthworm populations: a continuous maize field where pig slurry was applied, a rye-grass/maize rotation (3/1 year, respectively) also with pig slurry, and an old pasture sown with white clover and rye-grass.Pore space was quantified using a morphological approach and 2D image analysis. Undisturbed soil samples were impregnated with polyester resin containing fluorescent pigment. The images were taken under UV light, yielding a spatial resolution of 42 μm pixel−1. Pores were classified according to their size (which is a function of their area) and their shape. Hydraulic conductivity K(h) was measured using a disc infiltrometer at four water potentials: −0.05, −0.2, −0.6, and −1.5 kPa. The abundance and ecological categories groups of earthworms were also investigated.Continuous soil tillage causes a decrease in both abundance and functional diversity (cf. maize compared with old pasture) when soil tillage every 4 years causes only a decrease in abundance (cf. rotation compared with old pasture). There were no relationships between total porosity and effective porosity at h=−0.05 kPa. Image analysis was useful in distinguishing the functional difference between the three managements. Fewer roots and anecic earthworms resulted in fewer effective tubular voids under maize. There were fewer packing voids in the old pasture due to cattle trampling. Greater hydraulic conductivity in the pasture phase of rotation may arise from a greater functional diversity than in the maize and absence of cattle trampling compared with the pasture. We point to some significant differences between the three types of agricultural management.A better understanding is required of the influence of agricultural management systems on pore morphology. This study provides a new methodology in which we consider the earthworm activity as well as community in order to assess the effects of agricultural management on soil structure and water movement.  相似文献   

19.
《Soil biology & biochemistry》2001,33(12-13):1869-1872
Population densities of soil macrofauna were assessed in a field experiment with annually compacted treatments (applied to whole plots) and management treatments to repair initially compacted soil. Earthworms accounted for about half the macrofauna recovered during the experiment. Compaction of wet surface soil (water content>plastic limit) by agricultural machinery generally reduced numbers of macrofauna and earthworms. Annual compaction with a 10 Mg axle load on wet soil reduced mean macrofauna numbers from 70 to 15 m−2 and mean earthworm numbers from 41 to 2 m−2. Annual compaction with 6 Mg on soil drier than the plastic limit to a depth of 0.08 m had no adverse effect on the soil macrofauna. A 3-year pasture ley had more macrofauna (211 m−2) than a control treatment under cropping (29 m−2) but numbers declined when cropping was resumed.  相似文献   

20.
Earthworms play an important role in many soil functions and are affected by soil tillage in agricultural soils. However, effects of tillage on earthworms are often studied without considering species and their interactions with soil properties. Furthermore, many field studies are based on one-time samplings that do not allow for characterisation of temporal variation. The current study monitored the short (up to 53 days) and medium term (up to 4 years) effects of soil tillage on earthworms in conventional and organic farming. Earthworm abundances decreased one and three weeks after mouldboard ploughing in both conventional and organic farming, suggesting direct and indirect mechanisms. However, the medium-term study revealed that earthworm populations in mouldboard ploughing systems recovered by spring. The endogeic species Aporrectodea caliginosa strongly dominated the earthworm community (76%), whereas anecic species remained <1% of all earthworms in all tillage and farming systems over the entire study. In conventional farming, mean total earthworm abundance was not significantly different in reduced tillage (153 m−2) than mouldboard ploughing (MP; 130 m−2). However, reduced tillage in conventional farming significantly increased the epigeic species Lumbricus rubellus from 0.1 m−2 in mouldboard ploughing to 9 m−2 averaged over 4 years. Contrastingly, in organic farming mean total earthworm abundance was 45% lower in reduced tillage (297 m−2) than MP (430 m−2), across all sampling dates over the medium-term study (significant at 3 of 6 sampling dates). Reduced tillage in organic farming decreased A. caliginosa from 304 m−2 in mouldboard ploughing to 169 m−2 averaged over 4 years (significant at all sampling dates). Multivariate analysis revealed clear separation between farming and tillage systems. Earthworm species abundances, soil moisture, and soil organic matter were positively correlated, whereas earthworm abundances and penetration resistance where negatively correlated. Variability demonstrated between sampling dates highlights the importance of multiple samplings in time to ascertain management effects on earthworms. Findings indicate that a reduction in tillage intensity in conventional farming affects earthworms differently than in organic farming. Differing earthworm species or ecological group response to interactions between soil tillage, crop, and organic matter management in conventional and organic farming has implications for management to maximise soil ecosystem functions.  相似文献   

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