Effects of mulch location on banana weevil,soil and plant nutrients,soil water and biomass in banana fields

Major constraints to banana (Musa spp., genome group AAA) production, a dietary staple for over 70 million people in sub-Saharan Africa, are pest infestations, poor nutrition and inadequate water. Although mulch can improve soil water and nutrient status, many farmers believe it also promotes the proliferation of banana weevil (Cosmopolites sordidus), one of the most serious banana pests. In this study, we evaluated the effects of mulch location (mulch to base of banana pseudostem; mulch recessed 1 m from the pseudostem) on banana weevil, soil and plant nutrient status, soil water, and banana growth and development. After 3 years, the fully mulched plots had significantly more soil Ca and Mg than plots that did not receive mulch. Banana foliar K concentration was significantly higher in both mulch treatments (full and recessed) than in the control (no mulch) plots. The mulched plots had greater recharge after rainfall events and higher soil water contents during dry periods due to increased infiltration in the mulched plots. However, the mulched plots also exhibited significantly higher banana weevil densities and greater plant damage than the control plots. There was no difference in weevil damage with mulch location, although weevil density was higher in the fully mulched plots throughout most of the trial. Despite greater weevil damage, the treatments that were mulched yielded significantly heavier bunches. Hence the effects of the mulch on soil water infiltration and banana foliar nutrient status outweighed the detrimental effects of banana weevil damage.     

Utilization of MSW Compost In Nursery Stock Production

This three year study was conducted to evaluate the suitability of municipal solid waste (MSW) compost as a soil amendment or a mulch to suppress weeds in the production of field grown nursery stock. In the soil amendment experiment, compost was applied at the rates of 0, 56, and 112 t/ha and incorporated into the soil prior to planting. In the mulch/weed control experiment, 224 t/ha of compost was applied to one set of plots as a mulch after planting and compared to plots treated with herbicide and untreated controls. Each plot in both experiments contained four rows with one each of red maple (Acer rubrum L.), sugar maple (Acer saccharum Marsh.), white pine (Pinus strobus L.), and pin oak (Quercus palustris Muenchh.). Mortality and weed counts were determined during the first growing season. Annual measurements of crown height, crown width, and caliper (at the 1 foot level) were made the following three winters. Two inches of compost mulch (224 t/ha) provided adequate weed control only in the first year. Mowing suppressed the weeds that invaded the plots beyond the first year. For maples, first year mortality in plots mulched with 224 t/ha compost or amended with 112 t/ha compost was significantly less than unamended controls. In subsequent years, the mulched maples grew more than trees in the unamended controls. In the plots amended with 56 or 112 t/ha compost, sugar maples had increased height, canopy, and caliper growth compared to the unamended controls. The hearty pin oak saplings survived transplanting and there was a significant increase in caliper growth in plots amended with 112 t/ha (1 inch) of compost. Mortality of white pine increased when mulched with 224 t/ha compost. Increased mortality was most likely due to high concentrations of ammonium and soluble salts in the immature compost. Beyond the first year, there were no negative impacts on the growth of white pine from any of the compost treatments.     

Tillage and plastic mulch effects on soil properties and growth and yield of cocoyam (Colocasia esculenta) on an ultisol in southeastern Nigeria

Protected cultivation, mainly represented by plastic-film mulching, has greatly improved crop production worldwide since the 1950s. However, despite its widespread use in tropical USA, Europe and China, its use in sub-Saharan Africa is not widespread. A field experiment was conducted using cocoyam (Colocasia esculenta L. Schott) to evaluate the effects of two tillage systems (tilled and no-till) and plastic-film mulch (black and clear plastic-film mulch) on soil properties and cocoyam growth and yield in 2003 and 2004 planting seasons on a Typic paleudult in southeastern Nigeria. The experiment comprised six treatments and was laid out in the field using randomized complete block design replicated three times. Results showed that 70–80% of the corms emerged 7–8 days (21 days after planting [DAP]) earlier in both tilled and no-till plastic-film mulched plots when compared to the unmulched plots. At later stages of crop development, the plants in the tilled black plastic-film mulched plots were taller by 61–67% than those in the unmulched no-till plots, which had the lowest plant height (27–30 cm). At 98 DAP, there were no significant treatment differences in leaf area index (LAI) between tilled and no-till mulched plots with LAI of 15.5–19.8. However, LAI was reduced in both unmulched plots by 35–54% when compared to the mulched plots. On the average soil temperature was higher in plastic-film mulched plots than that under plots without mulch by about 2 °C. Results show significantly lower soil bulk density (between 1.10 and 1.26 Mg m⁻³) in both tilled clear and black plastic-film mulched plots when compared to the corresponding no-till clear or black plastic-film mulched plots (1.40–1.45 Mg m⁻³). For the two seasons studied volumetric water content (VWC) in tilled black plastic-film mulched plots were significantly higher than VWC in other mulched plots by between 10 and 38% in 2003 and between 17 and 30% in 2004. At harvest (270 DAP) the highest corm yield was obtained in tilled black plastic mulched plots (29.1 Mg ha⁻¹). This was higher (P = 0.05) than yields obtained in no-till, no mulch plots by 72%. Yields were also higher in tilled black plastic mulched plots when compared to tilled clear plastic mulched plots, no-till black plastic mulched plots and no-till clear plastic mulched plots by 29, 47 and 59%, respectively. These findings suggest that plastic mulched plots provide a better soil environment for cocoyam than unmulched plots and that tilled mulched plots especially tilled black plastic mulched plots provide superior edaphic environment for cocoyam when compared to other treatments used.     

Soil erosion on Alfisols in Western Nigeria: II. Effects of mulch rates

The effects of four rates of straw mulching on runoff and soil loss were compared with those of no-tillage treatments under natural rainfall conditions using field runoff plots of 25 × 4 m established at 1, 5, 10 and 15% slopes on the International Institute of Tropical Agriculture (IITA) research site near Ibadan, Nigeria. The four rates of straw mulching were 0, 2, 4 and 6 t/ha. The mean annual runoff was 50, 10, 4 and 2% of the total annual rainfall for mulch rates of 0, 2, 4 and 6 t/ha, respectively. Runoff from unmulched treatments was not related to slope. Runoff loss from no-till treatments was only 2% of the rain received. The mean soil losses for the rainstorms greater than 25 mm were 143, 16, 2 and 0.4 kg/ha per mm of rain received for mulched rates of 0, 2, 4 and 6 t/ha, respectively. The soil loss declined exponentially with increasing mulch rate with exponents ranging from approximately ?0.3 to ?0.7. The soil losses from the no-till plots were equal to those from plots that received mulch at the rate of 6 t/ha. Soil erodibility was significantly influenced by time after clearing, with maximum K reached two to three years after forest removal. The nutrient loss in runoff and eroded soil was significant only for unmulched treatments. The maximum annual loss of NO₃-N in runoff was about 15 kg/ha. The maximum annual loss of total N in eroded soil from unmulched plots was about 180 kg/ha, that of P, 5 kg/ha, and that of K, about 14 kg/ha.     

Analysis and simulation of soil organic‐carbon stocks in grassland ecosystems in SW Germany

Grassland extensification is followed by a change of soil organic‐matter (SOM) contents. In order to give a better assessment of these developments on grassland sites in SW Germany, the CENTURY Soil Organic Matter Model was used on five long‐term experimental sites under three different management practices (“Mowing”, “Mulching” (mowing without removal of the phytomass), and “Natural succession”). On these sites, soil‐organic‐carbon (SOC) monitoring was continuously done for soil depths of 0–4 and 4–8 cm from 1975 to 2002. The contents of organic carbon (OC) were at steady state or showed a slight decrease for the mulched and succession plots. Carbon contents of the mowed plots were decreasing. Measured C contents were transferred into stocks and compared with the simulated OC stocks. Linear regressions between observed and simulated C stocks were calculated separately for mulched and succession plots. The regressions for OC yielded significant relationships (R² = 0.8) for both kinds of plots. However, the model did not reproduce the short‐term dynamics of C stocks. Whereas SOC stocks on mulched and succession plots are expected to stay stable for the next decades according to the simulation, they are expected to decrease for a couple of years before stabilization on mowed plots.     

Response of fall greenhouse COS lettuce to clear mulch and nitrogen fertilizer

Application of clear plastic mulch with or without N fertilizer did not significantly increase (P > 0.05) yield of cos lettuce (Lactuca sativa L. cv. Paris Island), grown in Fall in a greenhouse in the Mediterranean mountains. Yield ranged from 31 to 38 kg/50 heads. Leaf NO₃‐N and total P levels were higher in mulched than unmulched plants, and in fertilized than in unfertilized plants, and always above the sufficiency level in all treatments. Soil levels of NO₃‐N were higher under mulched than unmulched plots, and under fertilized than unfertilized plots, which had more than 50 ppm NO₃‐N at harvest. This indicates ample supply of N and thus explains the lack of response to added N. It may be concluded that in mild climates and on soils with adequate N, lettuce will not respond to the use of clear mulch and N fertilizer.     

Film fully-mulched ridge-furrow cropping affects soil biochemical properties and maize nutrient uptake in a rainfed semi-arid environment

Abstract

This study evaluated the effects of plastic mulched ridge-furrow cropping on soil biochemical properties and maize (Zea mays L.) nutrient uptake in a semi-arid environment. Three treatments were evaluated from 2008 to 2010: no mulch (narrow ridges with crop seeded next to ridges), half mulch (as per no mulch, except narrow ridges were mulched), and full mulch (alternate narrow and wide ridges, all mulched with maize seeded in furrows). Compared to the no mulch treatment, full mulch increased maize grain yield by 50% in 2008 and 25% in 2010, but reduced yield by 21% in 2009 after low precipitation in early growth. Half mulch had a similar grain yield to no mulch in the three cropping years, suggesting half mulch is not an effective pattern for maize cropping in the area. Mulch treatments increased aboveground nitrogen (N) uptake by 21?34% and phosphorus (P) uptake by 21?42% in 2008, and by 16?32% and 14?29%, respectively, in 2010; but in 2009 mulching did not affect N uptake and decreased P uptake. Soil microbial biomass and activities of urease, β-glucosidase and phosphatase at the 0?15 cm depth were generally higher during vegetative growth but lower during reproductive growth under mulch treatments than no mulch. Mulching treatments increased carbon (C) loss of buried maize residues (marginally by 5?9%), and decreased light soil organic C (15?27%) and carbohydrate C (12?23%) concentrations and mineralizable C and N (8?36%) at harvest in the 0?20 cm depth compared with no mulch, indicating that mulching promotes mineralization and nutrient release in soil during cropping seasons. As a result of these biological changes, mineral N concentration under mulch was markedly increased after sowing in upper soil layers compared with no mulch. Therefore, our results suggest that mulched cropping stimulated soil microbial activity and N availability, and thus contributed to increasing maize grain yield and nutrient uptake compared with no mulch.     

Effect of peat moss‐shrimp wastes compost on the growth of barley (Hordeum vulgare L.) on a loamy sand soil

Abstract

A greenhouse experiment was conducted to determine the effect of peat moss‐shrimp wastes compost on barley (Hordeum vulgare L.) grown on a limed loamy sand soil. A control, four rates of compost applied alone and in combination with three rates of nitrogen, phosphorus, and potassium (NPK) chemical fertilizer were evaluated. Applications of compost to limed soil substantially enhanced the growth of barley over the control. When considering all treatments, the main effect of compost rates on straw yield, numbers of tillers, plant height, and number of ears was more important than that of fertilizer. A significant interaction on barley growth parameter values was obtained with compost and fertilizer rates. A combination of moderate application of compost and fertilizer gave in some instances, more yield than compost or fertilizer applied alone. Nutrient content of barley increased with rate of compost applied to soil over the control. A significant relationship was found between soil organic carbon (C) and straw yield, number of tillers, plant height and number of ears whereas grain yield was correlated with soil total N. Results from this study indicate that peat moss‐shrimp wastes compost could represent a potential means of renovating low fertility sand soils.     

Effect of termites and mulch on the physical rehabilitation of structurally crusted soils in the Sahel

The effectiveness of mulch and termite activity in the rehabilitation of the physical properties of crusted soil was studied in northern Burkina Faso (Province de Bam). A split plot design was used with three replications each being on one soil type. The soil types were Ferric Lixisol, Haplic Lixisol and Chromic Cambisol. The main factor was termite activity, and to this end dieldrin (0·50 kg a.i. ha⁻¹) was used to create plots without termite activity next to plots with termite activity. The subplots consisted of Pennisetum pedicellatum mulch, wood Pterocarpus lucens mulch and composite (wood+straw) mulch, applied at rates of 3, 6 and 4 t ha⁻¹, respectively. Two years after establishing the experiment, the combined effect of termite and mulch on the change in physical properties of the soil was measured. The parameters used for this assessment were porosity, saturated hydraulic conductivity and soil resistance to cone penetration. Soil water content was also measured. Termite activity was found to increase soil porosity, soil saturated hydraulic conductivity, improve soil water status and reduce soil bulk density and soil resistance to cone penetration. The only difference between bare plots and mulched plots without termites was in water content. This indicates that the mechanism whereby mulch improves the physical properties of crusted soil is mainly based on soil biology processes and to a limited extent on protecting soil against weather impact. © 1997 John Wiley & Sons, Ltd.     

Wheel traffic and tillage effects on runoff and crop yield

Traffic and tillage effects on runoff, soil water and crop production under rainfall were investigated over a period of 6 years on a heavy clay vertosols (vertisols) in Queensland, Australia. A split plot design was used to isolate traffic effects, while the cropping program and treatments were broadly representative of extensive grain production practice in the northern grain region of Australia. Treatments subject to zero tillage and stubble mulch tillage each comprised pairs of 90 m² plots, from which runoff was recorded. A 3 m wide controlled traffic system allowed one of each pair to be maintained as a non-wheeled plot, while the complete surface area of the other received a single annual wheeling treatment from a working 100 kW tractor.

Mean annual runoff from controlled traffic plots was 81 mm (36.3%) smaller than that from wheeled plots, while runoff from zero tillage was reduced by 31 mm (15.7%). Traffic and tillage effects appeared to be cumulative, so the mean annual runoff from controlled traffic and zero tillage plots, representing best practice, was 112 mm (47.2%) less than that from wheeled stubble mulch plots, representing conventional cropping practice. Rainfall infiltration into controlled traffic zero tillage soil was thus 12.0% greater than into wheeled stubble mulched soil. Rainfall/runoff hydrographs show that wheeling produced a large and consistent increase in runoff, whereas tillage produced a smaller increase. Treatment effects were greater on dry soil, but were still present in large and intense rainfall events on wet soil.

Plant available water capacity (PAWC) in the 0–500 mm zone increased by 10 mm (11.5%) and mean grain yields increased by 337 kg/ha (9.4%) in controlled traffic plots, compared with wheeled plots. Mean grain yield of zero tillage was 2–8% greater than that of stubble mulch plots for all crops except for winter wheat in 1994 and 1998. Increased infiltration and plant available water were probably responsible for increased mean grain yields of 497 kg/ha (14.5%) in controlled traffic zero tillage, compared with wheeled stubble mulch treatments. Dissipation of tractive and tillage energy in the soil is the apparent mechanism of deleterious effects on the soils ability to support productive cropping in this environment. Controlled traffic and conservation tillage farming systems appear to be a practicable solution.     

Soil management options for Alfisols in the semi-arid tropics: annual and perennial crop production

A field experiment was conducted in the semi arid tropics to study the effects of soil structural modification on cropping systems. The aim was to improve crop production and land resource protection using innovative soil management practices. Tillage, mulch and perennial/annual rotational based systems were compared for 5 years in an Alfisol at ICRISAT in India. Crop yield parameters, including grain and biomass yield, leaf area index, crop cover, and plant height were measured. Results indicate significant benefits to annual crop yield (maize, sorghum) from improved water supply due to mulching with farmyard manure or and rice straw, and due to rotation with prior-perennial crops. Grain yields were 16 to 59% higher in mulched treatments compared to unmulched treatments, with similar increases for fodder yields. Annual crop yields after 4 years of perennials were 14 to 81% higher than unmulched treatments, except for low fertility maize grown after buffel grass. The interaction with chemical fertility was less clear than for water supply. The results have implications for soil management throughout the semi-arid tropics.     

Zum Einfluß von obstbaulichen Bodenpflegemaßnahmen auf Lumbriciden,insbesondere Lumbricus terrestris L .

Influence of orchard soil management on lumbricids, especially Lumbricus terrestris L. In a long-term soil management experiment (apple orchard treated with cultivation methods such as grass mulch, grass harvest, straw mulch, clean cultivation) 6 plots were selected in order to study the abundance and biomass of earthworm populations. The following results were obtained: In all treatments with the exception of straw mulch L. terrestris represented the majority (60.5% on average) of the lumbricid population. Their share in the biomass amounted to 93.3%. The earthworm biomass was the highest in grass mulch; a close correlation was observed between the litter production (grass and leaves) and the biomass of L. terrestris. Added farm yard-manure on plots with grass mulch had no additional positive effect on earthworms. Although a higher earthworm biomass was found under grass mulch in comparison with straw mulch, the species diversity was higher in the latter. Clean cultivation had a highly detrimental effect on all earthworms, especially on the horizontally burrowing species. The annual nitrogen turnover by L. terrestris in mulched orchards was estimated to approx. 50 kg N/ha.     

Effects of vegetative mulches on growth of indigenous crops in the Kingdom of Tonga

As in many areas of the developing world, intensification of agriculture in Tonga, and other Pacific Islands, has put increased pressure on the soil resource. Two experiments were conducted to evaluate the effect of mulch on the growth and yield of two important food and fibre crops. The first was conducted on sloping land to evaluate the effect of guinea grass (Megathyrsus maximus ) mulch and hedgerows on taro [Colocasia esculenta (L.) Schott] yield, and in controlling soil erosion. The second compared the response of paper mulberry [Broussonetia papyrifera (L) Ventenot] to different management regimes of a grass fallow. Thick vegetative mulch increased taro corm yield by 81% and reduced soil loss by 50% compared to local farmer practice, and the soil loss from taro with mulch was comparable to the perennial cash hedgerow treatment. Mulch increased paper mulberry bark yield by 30% compared to the non‐mulch control. Comparative economic analysis showed that increased net profit in the mulched treatments compared to the non‐mulched control was T$2660/ha for taro and T$12 108/ha for paper mulberry. Considering that mulch is readily available to many farmers throughout the Pacific Islands and elsewhere in the tropics, it is recommended as a sustainable practice for crop production.     

On-farm evaluation of ridging and residue management options in a Sahelian millet-cowpea intercrop. 2. Crop development

Abstract. In the Sahel, promising technologies for agricultural intensification include millet stover mulching and ridging. A four year on‐farm experiment was set‐up in order to assess the effect of various combinations of these two technologies on crop development and yield in a millet (Pennisetum glaucum (L.) R. Br.) ‐ cowpea (Vigna unguiculata (L.) Walp.) intercropping system. Treatments included bare surface, ridging, a surface applied banded millet stover mulch (2 t ha^–1) and a banded millet stover mulch (2 t ha^–1) buried in ridges. The latter three treatments were implemented exclusively in the cowpea rows, with an annual rotation between the millet and cowpea rows. On bare and ridged plots, millet yields fell below 100 kg grain ha^–1 after the first year. This was ascribed mainly to soil acidification and loss of soil organic matter rather than to soil physical constraints or water availability despite extensive surface crusting and high soil penetration resistance and bulk density. Compared to the bare plots, ridging increased cowpea hay production by 330% over the four years which was attributed to lower soil penetration resistance and bulk density but also to a reduction of 0.15 cmol₊ kg^–1 exchangeable acidity in the ridges. Except during the severe drought year of 1997, millet grain yield in the banded mulch treatment remained fairly stable over time at 526 ± 9 kg ha^–1. However, a detailed analysis revealed yield compensation mechanisms between various yield components depending on the timing of occurrence of the abiotic stresses. Cowpea productivity was always higher in buried banded mulch plots than in surface applied banded mulch plots but the former treatment appeared unable to sustain millet yields. This decline was attributed to a greater nutrient uptake by cowpea and more rapid acidification in the buried mulch treatment compared to the banded mulch treatment.     

Influence of mulch C/N ratio and decomposition stage on plant N uptake and N availability in soil with or without wheat straw

Mulches can improve soil properties, but little is known about nutrient availability in mulched soil that contains plant residues and the effect of mulching with manures. The aim of this study was to determine the effects of mulching with high or low C/N organic materials, in which low C/N materials differed in decomposability, and the presence of wheat straw in the soil on plant growth and N uptake, soil N availability and microbial biomass N within about four months after mulching. Three organic materials were used: mature wheat straw (W, C/N 80), young faba bean shoots (FB, C/N 7), and sheep manure (SM, C/N 8). There were eight treatments differing in amendment methods (mulching or mixing with W or both) and mulching materials (W, FB or SM). Treatments that were only mulched with W, FB or SM are referred to as m‐treatments. In m/s‐treatments, after W was mixed into the soil, W, FB or SM were placed on the soil surface as mulch. Two other treatments included an unamended control and soil mixed with W. Wheat was planted 0, 35 or 70 days after mulching (referred to as 0, 35, and 70 DAM) and grown for 35 days. Faba bean mulch increased shoot dry weight, shoot N uptake and available N compared to wheat or sheep manure mulch, particularly in the m‐treatments. Shoot dry weight was higher in m‐treatments than corresponding m/s‐treatments with the same mulch type. Shoot N uptake was higher in 70 DAM than in 0 DAM in all treatments and 0.3 to three‐fold higher in m‐treatments than the corresponding m/s‐treatments. Microbial biomass N was higher in 0 DAM than in 35 and 70 DAM in most treatments and up to two‐fold higher in m/s‐treatments than the corresponding m‐treatments. Available N in m/s‐treatments was two to six‐fold higher than m‐treatments in 0 DAM, but differed little in older mulch ages of W and SM. It can be concluded that compared to soil with only mulch, mixing of wheat straw into soil reduced plant growth and N uptake, particularly in the early stages of mulching (0 and 35 DAM). However, the presence of wheat in mulched soil may provide a longer lasting source of N for plants and reduce the risk of N leaching from rapidly decomposing low C/N mulch due to greater microbial biomass N uptake than only soil with mulch.     

Effect of organic mulches on soil bacterial communities one year after application

The application of organic mulches as a soil cover is effective in improving the quality of soil. However, very little information is available on the effect of mulches on the soil microbial community. In this study, we investigated the effect of various organic mulches on soil dehydrogenase activity (DHA) and microbial community structures in the top 1 cm and 5 cm below the soil surface 1 year after application of the mulches. DHA was stimulated at both depths in plots mulched with grass clippings (GC), but was not significantly different from the control for the other mulch treatments. Fatty acid methyl ester (FAME) analysis and denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction-amplified 16S rDNA fragments were used to assess changes in the soil microbial community structure. Cluster analysis and principle component analysis of FAME profiles showed that only soil mulched with pine chips distinctively clustered from the other treatments. At the soil surface, bacterial DGGE profiles revealed that distinct shifts in several bacterial populations occurred in soils mulched with GC and eucalyptus yardwaste (EY), while DGGE profiles from soil at the 5 cm depth revealed no distinct changes. Changes in bacterial diversity at the soil surface under different mulches were calculated based on the number of bands in the DGGE profile using the Shannon-Weaver index of diversity ( H). Compared to the control ( H =0.9), the GC- and EY-treated soils showed slightly increased bacterial diversity, with an H of 1.1 and 1.0, respectively. These results indicate that the long-term effect of organic mulches on the soil microbial activity and community structure is highly dependent upon the type of mulch and is mostly exerted in the top few centimeters of the soil profile.     

免耕覆盖还田下玉米秸秆氮素的去向研究

采用田间微区试验,以15N标记的玉米秸秆为研究对象,研究了免耕覆盖还田下玉米秸秆氮素经过4个生长季后的作物累积利用率、在土壤(0~60 cm)的残留率以及损失情况。试验共设2个处理:TS1为第1年15N标记秸秆覆盖还田,此后秸秆不还田;TS2为第1年15N标记秸秆覆盖还田,此后每年以非标记秸秆还田。结果表明:经过4个生长季后,两个处理间的玉米籽粒、秸秆的累积产量及总氮素吸收量的差异均不显著。在TS1处理中,秸秆氮素在籽粒和秸秆中的累积回收率分别为14.2%和6.7%,并分别高于TS2处理的12.4%和5.8%。与作物的累积回收率相比,更多的秸秆氮素被保持在土壤中。在TS1和TS2处理中,秸秆氮素在土壤中的残留率分别为40.9%和73.8%,而损失率分别为38.6%和8.1%。与TS1处理相比,TS2处理中较高的土壤微生物生物量碳和氮以及较低的矿质态秸秆氮的含量,说明连续秸秆还田在一定程度上提高了最初还田秸秆氮素在土壤中的微生物固持并降低了秸秆氮素的淋失风险,从而显著提高秸秆氮素在土壤-植物系统中的总回收率。因此,在温带农田生态系统中,长期的免耕结合秸秆覆盖还田可促进秸秆氮素的积累,这对提高和保持土壤氮素含量和稳定性具有重要的意义。     

Soil erosion on Alfisols in Western Nigeria: V. The changes in physical properties and the response of crops

Erosion-induced changes in the physical characteristics of the surface soil under different soil and crop management treatments were monitored over a period of two years. These studies were conducted on field runoff plots established on natural slopes of 1, 5, 10 and 15%. The soil and crop management treatments consisted of bare-fallow, maize-maize (plowed and mulched), maize-maize (plowed), maize-cowpeas (no-till) and cowpeas-maize (plowed).Soil erosion increased the gravel content and decreased the silt and clay contents of the surface horizon. The moisture retention capacity of the surface soil decreased significantly. The infiltration rate decreased from 3.5 cm/min on all plots in February 1972 to 0.2 cm/min under bare-fallow, to 0.6 cm/min under maize-maize (mulch), to 1.5 cm/min under maize-cowpeas (no-till) and to 0.1 cm/min under maize-maize (plowed) in February 1974. Maize yields on the mulch and no-till treatments were maintained while those on plowed plots declined. Artificial soil removal resulted in significant reductions of maize and cowpea yields.     

Invertebrates and nutrients in a Mediterranean vineyard mulched with subterranean clover (Trifolium subterraneum L.)

Summary In the 25-year-old vineyard of a farm near the Maremma National Park (Central Italy), replicate plots were established with a mulch of Trifolium subterraneum L. or cultivation and two levels of fertilizer. The mai objective of this research was to analyse responses by soil invertebrates and nutrients after introducing a herbaceous component into the system; the yield was also considered. The greater availability of organic substrate and the reduced cultivation as a result of green mulching increased the soil mesofauna biomass, especially detritivores. With time, a significant difference became evident between the populations of invertebrates present in the mulched plots and those in the cultivated plots. Over 2 years, most nutrients (Ca, K, P, and N) were significantly increased in the mulched plots compared to the cultivated plots. Grape yields were consistently higher in the bare plots. No significant differences were found in fertilizer effects.     

The biological and physical role of mulch in the rehabilitation of crusted soil in the Sahel

Abstract. During three consecutive years (1993–1995) a split-plot design with three replications was used to study the biological and physical role of mulch in the improvement of crusted soil water balance and its productivity in the north of Burkina Faso. The main treatment was the use of an insecticide, to obtain plots with and without soil fauna (SF and NSF). The subsidiary treatment consisted of four mulch types randomly applied on subplots. These were straw of Pennisetum pedicellatum applied at 3 t ha⁻¹, woody material of Pterocarpus lucens applied at 6 t ha⁻¹ and composite (woody material and straw) treatments applied at 4 t ha⁻¹. In addition there was a control, with no mulch (bare plot). Data on soil faunal activity, runoff, sediment accumulation from wind blown soil, vegetation cover and vegetation dry matter yield were collected on all plots.
The biological activity (mainly termites) in mulched plots was the key element in the efficacy of mulching to rehabilitate crusted soil. Water infiltration and dry matter yield were statistically lower on NSF plots than on SF plots and runoff and dry matter yield were not different from the values obtained on bare plots. A significant correlation was found between runoff, all vegetation data and termite-voids. Sediment accumulation due to the physical barrier of the mulch was not found to be a significant factor in the improvement of vegetation performance and the reduction of runoff.