Improve Soil Physical Properties Research Articles

Physical Effects of Organic Matter Amendment of a Southeastern US Coastal Loamy Sand

We tested 12 organic sources as amendments for E horizon and a mixture of E and Bt horizons of a southeastern coastal loamy sand. Amendments were intended to increase carbon and improve soil physical properties. Amendments included biochar, cellulose, corn (Zea mays L.) stalk, corn starch, cotton (Gossypium hirsutum L.) hull, cotton meal, manure residual, peanut (Arachis hypogaea L.) hull, poultry litter, soybean (Glycine max L. Merr.) plant, wheat (Triticum aestivum L.) straw, and wood shavings. Amendments were added at a rate of ∼1% (wt wt−1) or ∼22 Mg ha−1 organic carbon content to 450 g soil and incubated in a laboratory for 60 days. Cellulose, corn stalk, and corn starch amendments had the most dry-sieved aggregation at 35% versus the control, peanut hull, poultry litter, wood shavings, and biochar, which had the least at 21%. Biochar, wood shavings, and corn starch–amended treatments had the highest penetration resistances at 0.25 to 0.38 MPa above the mean; cellulose and cotton meal had the lowest at 0.24 to 0.32 MPa below the mean. Poultry litter and manure residual–amended treatments needed the least amount of water added to maintain 0.1 (wt wt−1); cellulose, biochar, and soybean plant needed the most. All needed less than the control. Mixing Bt horizon into the E improved most physical properties. All amendments improved some physical properties—more carbon, more aggregation, or reduced soil penetration resistance. Biochar retained 26% of its carbon, more than other amendments that retained 13% to 23%.

Effect of Rice Mill Wastes Application on Selected Soil Physical Properties and Maize Yield (Zea mays l.) On an Ultisol in Abakaliki Southeastern Nigeria

An experiment was carried out in 2008, 2009 and 2010 (residual) cropping season at Teaching and Research Farm of Faculty of Agriculture and Natural Resources Management, Ebonyi State University, Abakaliki to determine the long term effect of burnt and unburnt rice mill wastes application on soil physical properties and maize yield. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replicates. Seven treatments were included in the study: burnt rice mill waste at 10 and 20 t ha-1(BW10) and (BW20), unburnt rice mill waste at 10 and 20 t ha-1(UW10) and (UW20), mixture of burnt + unburnt rice mill waste (1:1) at 10 and 20 t ha-1(BUW10) and (BUW20), and a control (C). The results showed that rice mill wastes significantly (P BUW20> BUW10>UW20>BW10>UW10>C and BUW20>BUW10>BW20> UW20>BW10>UW10>C. Control recorded the lowest value of crop grain yield (0.12 t ha-1) in 2010 cropping season. At rate of 20 t ha-1 BW, BUW and UW recorded highest maize grain yield of 4.18, 4.06 and 1.70 t ha-1 in 2008, 2009 and 2010 cropping seasons, respectively. Therefore, rice mill wastes at these rates studied (10 and 20 t ha-1) could be used as soil amendment since it improved soil physical properties and increased maize yield. Key words: Aggregate stability, hydraulic conductivity, maize yield, organic matter, and rice mill wastes

Response of hot pepper (Capsicum annuum L.) to mulching practices under planted greenhouse condition

Mulch is considered a desirable management technology for conserving soil moisture, improving soil temperature and soil quality. This study aimed to investigate soil conditions and hot pepper (Capsicum annuum L) performance in terms of leaf photosynthetic capacity, fruit yield and quality, and irrigation water use efficiency (IWUE) under such practices in greenhouse condition. A field experiment across 3 years was carried out with four types of mulch (without mulch [CK], wheat straw mulch [SM], plastic film mulch [FM], and combined mulch with plastic film and wheat straw [CM]). Mulch could improve soil physical properties regardless of mulch materials. FM and CM treatments improved soil moistures status and soil temperature in comparison to CK control, while SM increased soil water content and decreased soil temperature. Mulch increased leaf net photosynthesis rate (P(N)), stomatal conductance to water vapor (gs), intercellular CO(2) concentration (Ci), and transpiration rate (E), but declined instant water use efficiency (WUEi). No significant effect of mulch application on chlorophyll fluorescence was existent for the entire growth season. Fruit yield and irrigation water use efficiency (IWUE) showed some increment under all the mulch conditions. Compared to CK, the yield was enhanced by 82.3%, 65.0%, and 111.5% in 2008; 38.1%, 17.4%, and 46.5% in 2009; and 14.3%, 6.5%, and 19.6% in 2010 under SM, FM, and CM conditions, respectively. Although FM produced better fruit quality than other treatments, CM is the recommended practice for hot pepper cultivation in greenhouse condition due to working well to facilitate soil condition (moisture and temperature), plant growth, and marketable yield. (C) 2011 Elsevier B.V. All rights reserved.

Addition of Cover Crops Enhances No‐Till Potential for Improving Soil Physical Properties

Inclusion of cover crops (CCs) may be a potential strategy to boost no‐till performance by improving soil physical properties. To assess this potential, we utilized a winter wheat (Triticum aestivum L.)–grain sorghum [Sorghum bicolor (L.) Moench] rotation, four N rates, and a hairy vetch (HV; Vicia villosa Roth) CC after wheat during the first rotation cycles, which was replaced in subsequent cycles with sunn hemp (SH; Crotalaria juncea L.) and late‐maturing soybean [LMS; Glycine max (L.) Merr.] CCs in no‐till on a silt loam. At the end of 15 yr, we studied the cumulative impacts of CCs on soil physical properties and assessed relationships between soil properties and soil organic C (SOC) concentration. Across N rates, SH reduced near‐surface bulk density (ρb) by 4% and increased cumulative infiltration by three times relative to no‐CC plots. Without N application, SH and LMS reduced Proctor maximum ρb, a parameter of soil compactibility, by 5%, indicating that soils under CCs may be less susceptible to compaction. Cover crops also increased mean weight diameter of aggregates (MWDA) by 80% in the 0‐ to 7.5‐cm depth. The SOC concentration was 30% greater for SH and 20% greater for LMS than for no‐CC plots in the 0‐ to 7.5‐cm depth. The CC‐induced increase in SOC concentration was negatively correlated with Proctor maximum ρb and positively with MWDA and cumulative infiltration. Overall, addition of CCs to no‐till systems improved soil physical properties, and the CC‐induced change in SOC concentration was correlated with soil physical properties.

콩 재배 시 크림손클로버, 헤어리벳치, 호밀 예취물 피복이 잡초 발생과 콩 생육 및 수량에 미치는 영향

본 연구는 콩 재배시 동계 피복작물인 크림손클로버, 헤어리벳치, 호밀의 예취물 피복이 잡초발생과 콩생육 및 수량에 미치는 영향을 알아보고자 실시되었다. 연구 결과 크림손클로버, 호밀, 헤어리벳치 피복구에서 모두 이른 봄 잡초 억제율이 높았으며, 콩 정식 64일 후에도 헤어리벳치 피복구는 87.6%, 호밀 피복구는 72.0%로 콩의 초관이 형성될 때까지 높은 잡초억제율이 유지되었다. 그러나 크림손클로버 피복구는 시간에 흐름에 따라 잡초억제율 감소폭이 커서 여름잡초가 많이 발생한 콩 정식 64일 후에는 4.1%로 현저하게 감소되었다. 헤어리벳치 피복구는 월년생과 다년생잡초에 대한 억제율이 98.2%로 가장 높았고, 호밀 피복구는 광엽잡초 억제율이 57.6%인 반면, 화본과잡초 억제율은 93.8%로 광엽잡초 보다 화본과 잡초에 대한 억제 효과가 높았다. 크림손클로버 피복구에서는 다년생과 월년생잡초 억제효과가 거의 없었으며, 광엽잡초에 대한 억제효과도 없었다. 콩의 후기 영양생장기에 초장을 조사한 결과 무피복에 비해 크림손클로버, 헤어리벳치, 비닐 피복구에서 각각 6.9%, 20.2%, 22.0% 초장이 더 길었으나, 호밀 피복구는 오히려 초장이 짧았다. 콩의 입비대시에는 호밀 피복구의 콩 생육이 다소 회복이 되었으며, 수확기때 콩 수량은 헤어리벳치 피복구 <TEX>${\fallingdotseq}$</TEX> 비닐 피복구 > 크림손클로버 피복구 <TEX>${\fallingdotseq}$</TEX> 호밀 피복구 > 무피복구 순이었다. Weed control using cover crops has advantages of agricultural and environmental aspects which prevent soil erosion, nitrogen supply, improving soil physical properties, reduction of nitrate leaching, organic supply and control of weed occurrence. In this study, we evaluated the inhibitory effects of cover crops on the weed occurrence, growth and yield of soybean in cover crop-soybean cropping system. The treatments were consisted of 4 different mulching system such as crimson clover (Trifolium incarnatum) residue, hairy vetch (Vicia villosa) residue, rye (Secale cereale) residue and Polyethylene plastic(P.E.) mulch with no mulch treatment (control). Three cover crops were grown throughout the winter and were cut in next spring. And then 13 days old soybean seedlings were transplanted in each treatment field on <TEX>$4^{th}$</TEX> June. Crimson clover, hairy vetch and rye mulch treatments reduced weeds density compared to control (73.0%, 98.0% and 85.3% respectively), on <TEX>$26^{th}$</TEX> May. However, weed inhibition rate of crimson clover mulch treatment was sharply decreased to 4.17% on <TEX>$6^{th}$</TEX> August, while hairy vetch and rye mulch treatments were continued high weed inhibition rate with 87.6% and 72.0% respectively. There was no inhibition effect of perennial, winter annual and broadleaf weeds inhibition in crimson clover mulch treatment. Height of soybean in crimson clover, hairy vetch and P.E. mulch treatment was 6.9%, 20.2% and 22.0% higher than that of control. But height of soybean in rye mulch treatment was lower than control on <TEX>$13^{th}$</TEX> July. At harvesting, yields of soybean were in order of hairy vetch mulch treatment<TEX>${\fallingdotseq}$</TEX> P.E. mulch treatment > crimson clover mulch treatment <TEX>${\fallingdotseq}$</TEX> rye mulch treatment > control.

Long-Term Effect of Organic and Mineral Fertilization on Soil Physical Properties Under Greenhouse and Outdoor Management Practices

To evaluate the use of organic amendments as an alternative to conventional fertilization, a 10-year experiment on a loam soil was conducted under a crop rotation system in both greenhouse and outdoor plots applied with chemical fertilizers (NPK) and vegetal compost (organic fertilizer) in the Guadalquivir River Valley, Spain. The effect of these two different fertilization regimes on the soil physical properties was evaluated. Soil organic carbon (OC), soil bulk density (BD), soil water retention (WR), available water content (AWC), aggregate stability (AS), and soil physical quality (Dexter's index, S) were determined. The use of organic fertilizer increased OC and resulted in a significant increase in AS and a decrease in BD compared to the mineral fertilizer application in both greenhouse and outdoor plots. The outdoor plots showed the lowest BD values whereas the greenhouse plots showed the highest AS values. In the last years of the 10-year experiment the S parameter was significantly higher in organic fertilizer plots, especially for greenhouse plots. At the end of the study period, there were no significant differences in WR at field capacity (FC) between treatments in both systems; the AWC was also similar in the greenhouse plots but higher in the mineral outdoor plots. In mineral fertilizer treatments, a small improvement in the physical properties was also observed due to the utilization of less aggressive tillage compared with the previous intensive cropping system. Physical soil properties were correlated with soil OC. The sustainable management techniques such as the use of organic amendments and low or no tillage improved soil physical properties, despite the differences in management that logically significantly affected the results.

The Biochar Effect: plant resistance to biotic stresses

Summary. Biochar (charcoal) is the solid co-product of pyrolysis, the thermal degradation of biomass in the absence of oxygen. Pyrolysis also yields gaseous and liquid biofuel products. There is a growing interest worldwide in the pyrolysis platform, for at least four reasons: (i) pyrolysis can be a source of renewable biofuels; (ii) many biomass waste materials can be treated by pyrolysis and thus converted into a fuel resource; (iii) long-term sequestration of carbon dioxide which originated in the atmosphere may result from adding biochar to soil, and (iv) biochar soil amendment contributes to improved soil fertility and crop productivity. Currently, however, very little biochar is utilized in agriculture, in part because its agronomic value in terms of crop response and soil health benefits have yet to be quantified, and because the mechanisms by which it improves soil fertility are poorly understood. The positive effects of biochar on crop productivity under conditions of extensive agriculture are frequently attributed to direct effects of biochar-supplied nutrients and to several other indirect effects, including increased water and nutrient retention, improvements in soil pH, increased soil cation exchange capacity, effects on P and S transformations and turnover, neutralization of phytotoxic compounds in the soil, improved soil physical properties, promotion of mycorrhizal fungi, and alteration of soil microbial populations and functions. Yet, the biochar effect is also evident under conditions of intensive production where many of these parameters are not limited. Biochar addition to soil alters microbial populations in the rhizosphere, albeit via mechanisms not yet understood, and may cause a shift towards beneficial microorganism populations that promote plant growth and resistance to biotic stresses. In addition to some scant evidence for biochar-induced plant protection against soilborne diseases, the induction of systemic resistance towards several foliar pathogens in three crop systems has been demonstrated. There are indications that biochar induces responses along both systemic acquired resistance (SAR) and induced systemic resistance (ISR) pathways, resulting in a broad spectrum controlling capacity in the canopy. This review examines the effects of biochar soil amendment on the different soil-plant-microbe interactions that may have a role in plant health. Improvement of plant responses to disease can be one of the benefits gained from applying biochar to soil.

Review: The effects of soil compaction on root penetration, pasture growth and persistence

A review of the literature shows that soil compaction by stock treading has been an issue for New Zealand farmers for over half a century. Soil compaction restricts root penetration resulting in poor anchorage and susceptibility of plants to uprooting during grazing. In addition, access to moisture and soil nutrients is reduced which decreases the fitness of the sward under stress conditions. Mechanical treatment of compacted soil improves soil physical properties but beneficial effects on pasture growth have been less readily demonstrated. Options to reduce the impact of soil compaction on pasture persistency include better soil management to reduce the incidence and severity of compaction and, in the longer term, new grasses with root and shoot traits that mitigate the effects of compaction. Keywords: roots, ryegrass, soil compaction, soil moisture, soil nutrients, trampling

Robinia pseudoacacia leaves improve soil physical and chemical properties

The role of the leaves of Robinia pseudoacacia L., which is widely distributed in the arid lands, on improving soil physical and chemical properties was analyzed at various incubation periods. The incubated soils added with 0, 25, 50 and 75 g Robinia pseudoacacia leaves were tested after consecutive incubation intervals of 6, 8 and 10 months and the different soil parameters were measured. The results showed the increases in organic matter (OM), extractable K, cation exchange capacity (CEC), aggregate stability and water holding capacity, but the decreases in pH value and bulk density after 6 months' incubation. The gradual decrease in change rates of soil properties indicated less microbial population and organic residual mineralization under acidic conditions, which were resulted from fast decomposition of leaves after the first 6 months incubation. The increases in soil organic matter content, extractable K, CEC, aggregate stability and water holding capacity and the decreases in soil pH and bulk density provide favorable conditions for crop’s growth.

Organic Maize Growth and Mycorrhizal Root Colonization Response to Tillage and Organic Fertilization

The influence of conventional and no-tillage on mycorrhizal root colonization, soil properties and yield, was studied for 2 years in an experimental field of organic maize, fertilized by cattle manure or by seaweed compost. The no-tillage system improved soil macroporosity, increased organic carbon content, and enhanced the mean weight diameter of soil aggregates. Similarly, it had a positive effect on plant growth. Root density, leaf area index, biomass, grain yield and mycorrhizal root colonization were significantly affected by tillage system. Fertilization with manure and compost improved soil structure and aeration, thus favoring a higher mycorrhizal colonization of organic maize. The improved soil physical properties were positively related to mycorrhizal root colonization. High correlation coefficients of determination (r2) were also found between mycorrhizal root colonization and plant characteristics. It is concluded that the no-tillage system can improve the productivity of organic agriculture via pronounced arbuscular mycorrhizal root colonization.

Tillage and fertilizer effects on some soil properties, leaf nutrient concentrations, growth and sweet potato yield on an Alfisol in southwestern Nigeria

Tillage and fertilizer influenced soil characteristics through their effects on soil properties which in turn affect crop performance. Field experiments were conducted during 2006 and 2007 cropping seasons on an Alfisol (Oxic Tropuldalf) at Owo in the forest-savanna transition zone of Nigeria to evaluate the effect of tillage and fertilizer types on soil properties and sweet potato yield ( Ipomoea batatas L.). Two tillage treatments namely: zero tillage (ZT) and conventional tillage (CT) were combined with each of NPK-15-15-15 fertilizer at 250 kg ha −1, poultry manure (PM) at 10 t ha −1, combined application of 125 kg ha −1 NPK 15-15-15 fertilizer + 5 t ha −1 poultry manure and a control (no fertilizer/manure). The experiment was laid out on a randomized complete block design in a factorial combination of eight treatments that were replicated three times. The surface soil (0–15 cm depth) was chemically analysed before and after crop harvest and some selected soil physical properties, leaf nutrient concentrations, growth and sweet potato yield were determined. Conventional tillage plots had significantly lower soil bulk density (1.30 Mg m −3) than zero tillage plots and resulted in higher leaf N, P, K, Ca and Mg and tuber yield of sweet potato compared with zero tillage. Soil water content was higher, whereas temperature was lower, in zero tillage than conventional tillage. Zero tillage had significantly higher concentrations of soil pH, organic C, N, P, K, Ca and Mg for surface soil (0–15 cm depth). Conventional tillage increased mean tuber yield of sweet potato by 30% compared with planting on untilled zero soil. Application of poultry manure alone and complementary application of NPK fertilizer and poultry manure reduced bulk density and temperature and increased soil water content and porosity, whereas NPK fertilizer did not improve soil physical properties. Compared with control, poultry manure alone, NPK fertilizer alone and complementary application of NPK fertilizer and poultry manure increased soil total N, available P, and exchangeable K, Ca and Mg concentrations as well as leaf N, P, K, Ca and Mg concentrations. Poultry manure tended to improve soil pH, SOC, N, Ca and Mg compared with NPK fertilizer. Combined application of sub-optimal rates of NPK fertilizer and poultry manure gave higher soil and leaf N, P and K concentrations, vine length, vine girth, leaf area and tuber yield compared with NPK fertilizer or poultry manure alone. Compared with control, NPK fertilizer, poultry manure and NPK fertilizer plus poultry manure increased tuber yield by 39, 45 and 83%, respectively. Conventional tillage in combination with NPK fertilizer plus poultry manure gave the highest tuber yield of sweet potato.

PENGARUH REKLAMASI LAHAN TERHADAP SIFAT FISIKA DAN EROSI PADA LAHAN ALANG-ALANG

A research about utilization of cylindrica biomass as an OM source was conducted to improve physical properties and to reduce soil erosion of degraded land and. The area of degraded land is quite large and the cylindrical biomass as a soil ameliorant is enough amount to use. The research was aimed to evaluate the effect of cylindrical biomass to improve properties and to reduce erosion of degraded Ultisol. Cylindrica biomass was treated as mulch as well as compost, sprayed with Round up, and removed from the land as farmers used to do. The field research was designed in Randomized Block Design (RBD). The result showed that cylindrical biomass was able to improve soil physical properties (BD, TP, infiltration rate) and to reduce erosion lower than the tolerated one. Keywords: land reclamation, erosion, tolerated erosion

Root length density and carbon content of agroforestry and grass buffers under grazed pasture systems in a Hapludalf

Enhancement of root development helps to improve soil physical properties, carbon sequestration, and water quality of streams. The objective of this study was to evaluate differences in root length density (RLD) and root and soil carbon content within grass buffer (GB), agroforestry buffer (AgB), rotationally grazed pasture (RG) and continuously grazed pasture (CG) treatments. Pasture and GB areas included red clover (Trifolium pretense L.) and lespedeza (Kummerowia stipulacea Maxim.) planted into fescue (Festuca arundinacea Schreb.) while AgB included Eastern cottonwood trees (Populus deltoids Bortr. ex Marsh.) planted into fescue. One-meter deep soil cores were collected from each treatment in August 2007 and 2008 with a soil probe. Three soil cores were sampled at six replicate sampling positions. Soil cores were collected in plastic tubes inserted inside the metal soil probe. Soils were segregated by horizons, and roots were separated into three diameter classes (0–1, 1–2, >2 mm) by soil horizon. Root length was determined using a flatbed scanner assisted with computer software. Buffer treatments (167 cm/100 cm3) had 4.5 times higher RLD as compared to pasture treatments (37.3 cm/100 cm3). The AgB treatment had the highest (173.5 cm/100 cm3) RLD and CG pasture had the lowest (10.8 cm/100 cm3) value. Root carbon was about 3% higher for the buffers compared to RG treatment. Soil carbon was about 115% higher for the buffers compared to pasture treatments. Results from this study imply that establishment of agroforestry and GB on grazed pasture watersheds improve soil carbon accumulation and root parameters which enhance soil physical and chemical properties thus improving the environmental quality of the landscape.

Soil Response to Long‐Term Cropping Systems on an Argiustoll in the Central Great Plains

Development or identification of cropping systems that conserve soil and water, sequester soil organic C (SOC), and improve soil productivity is a high research priority, particularly in semiarid regions. We assessed the impacts of 33‐yr cropping systems on near‐surface soil structural, compaction, and hydraulic properties and their relationships with SOC concentration on a nearly level Crete silty clay loam (fine, smectitic, mesic Pachic Argiustoll) in the central Great Plains. Five cropping systems (sorghum [Sorghum bicolor (L.) Moench]–fallow [SF], continuous sorghum [SS], winter wheat [Triticum aestivum L.]–sorghum–fallow [WSF], wheat–fallow [WF], and continuous wheat [WW]) under reduced tillage (RT) and no‐till (NT) were studied. Cropping systems significantly impacted soil properties. Wet aggregate stability and aggregate water repellency in WW were two to five times greater than in other rotations for the 0‐ to 2.5‐cm soil depth. The WW and WSF retained 10 to 16% more water than SF between 0 and −3 kPa matric potentials under NT. The WW reduced bulk density (ρb) and increased cumulative water infiltration over other rotations under NT. The WW increased SOC concentration over all other rotations under NT and SF and SS under RT in the 0‐ to 2.5‐cm depth. The SF affected soil properties more adversely than WF. Wet aggregate stability, water repellency, total porosity, cumulative water infiltration, and soil water retention increased while ρb decreased with an increase in SOC concentration. Wet aggregate stability increased with an increase in aggregate water repellency (r &gt; 0.80, P &lt; 0.001). Overall, intensification of cropping systems such as WW coupled with NT improved soil physical properties and increased SOC concentration.

Improvement of Soil Physical Properties and Aggregate-Associated C, N, and P After Cropland was Converted to Grassland in Semiarid Loess Plateau

AbstractBecause of overcultivation in the semiarid Loess Plateau during the past half century, soil erosion has become a serious problem in maintaining a sustainable ecosystem. To find an effective way to overcome soil erosion, we investigated the changes of soil pH, soil bulk density, soil aggregat

Legumes in the Cropping Systems of Southeastern Nigeria

Soil nutrient and physical status in small holder farms in southeastern Nigeria are subjected to debilitating effects of continuous cropping without adequate efforts towards replenishment and conservation to ensure sustainability of soil resources. Although inorganic fertilizers are quick acting for soil nutrient enhancement, to guarantee soil health they must be used within the context of integrated soil fertility management relative to soil type and other climatic conditions. On the other hand, apart from maintaining required nutrient levels, the use of appropriate crop combinations and arrangements in farmers' fields can improve soil health. Leguminous plants including tree, shrub and annual species have been determined to be useful components in such systems. These species can contribute immensely to soil carbon and other mineral contents in addition to improving soil physical properties. Apart from their high edible protein content, some leguminous seeds also have high phytate content, which should enhance the bioavailability of Zn, making them good nutrient sources in human and animal nutrition. However, indigenous leguminous tree, shrub, and grain legume species are currently underutilized in the common cropping systems on smallholder farms. While tree species are lost through logging, with very limited research toward their improvement, research on grain legumes has been limited in this zone resulting in the loss of indigenous grain species. Low available soil P is another constraint to legume cultivation in this region that has to be addressed through well coordinated agronomic research. Increased and sustainable food production on small holder farms in southeastern Nigeria is possible with improved practices within the prevailing cropping systems. This is achievable with intensive breeding, agronomic and utilization studies on legume species in the cropping systems.

Statut poral des sols cultives dans la zone cotonniere ouest du Burkina Faso

CULTIVATION-INDUCED EFFECTS ON SOIL POROSITY IN THE WESTERN COTTON AREA OF BURKINA FASO The improvement of soil physical properties is of paramount importance in ensuring sustainable crop production. A diagnostic study on soil porosity was carried out on a Ferric Lixisol and a Ferric Luvisol from Burkina Faso, in order to assess the cumulative effects of cropping systems. One hundred-and-one plots were sampled based on the typology of major cropping systems (shifting, cyclic, continuous cultivation) and tillage intensity (occasional, biennial, annual ploughing). Soil porosity was measured within the top soil layer (015 cm), with a rubber-balloon densitometer, in situ, and with a mercury porosimeter. The results showed that soil cultivation increased the porosity of soils under cyclic fallow, from 41 to 45 %. But, these modifications affected mainly soil structural porosity (macroporosity). Annual ploughings induced, in the long-term, a loss, by two points, of soil structural porosity, as compared to shifting cultivation fallow systems. They contributed to combine soil macropore groups (50 - 100 µm) and micropores (10 µm) under natural fallow into a new pores group of equivalent diameters (15 - 25 µm).

Economical and environmental implications of solid waste compost applications to agricultural fields in Punjab, Pakistan

Application of municipal solid waste compost (MSWC) to agricultural soils is becoming an increasingly important global practice to enhance and sustain soil organic matter (SOM) and fertility levels. Potential risks associated with heavy metals and phosphorus accumulations in surface soils may be minimized with integrated nutrient management strategies that utilize MSWC together with mineral fertilizers. To explore the economic feasibility of MSWC applications, nutrient management plans were developed for rice-wheat and cotton-wheat cropping systems within the Punjab region of Pakistan. Three-year field trials were conducted to measure yields and to determine the economic benefits using three management strategies and two nutrient doses. Management strategies included the application of mineral fertilizers as the sole nutrient source and application of mineral fertilizers in combination with MSWC with and without pesticide/herbicide treatments. Fertilizer doses were either based on standard N, P and K recommendations or on measured site-specific soil plant available phosphorus (PAP) levels. It was found that combining MSWC and mineral fertilizer applications based on site-specific PAP levels with the use of pesticides and herbicides is an economically and environmentally viable management strategy. Results show that incorporation of MSWC improved soil physical properties such as bulk density and penetration resistance. The PAP levels in the surface layer increased by the end of the trials relative to the initial status. No potential risks of heavy metal (Zn, Cd, Cr, Pb and Ni) accumulation were observed. Treatments comprised of MSWC and mineral fertilizer adjusted to site-specific PAP levels and with common pest management showed highest cumulative yields. A basic economic analysis revealed a significantly higher cumulative net profit and value-to-cost ratio (VCR) for all site-specific doses.

Changes of soil organic carbon and its fractions in relation to soil physical properties in a long-term fertilized paddy

Soil organic carbon (SOC) has an important role in improving soil quality and sustainable production. A long-term fertilization study was conducted to investigate changes in SOC and its relation to soil physical properties in a rice paddy soil. The paddy soils analyzed were subjected to different fertilization practices: continuous application of inorganic fertilizers (NPK, N–P–K = 120–34.9–66.7 kg ha −1 yr −1 during 1967–1972 and 150–43.7–83.3 kg ha −1 yr −1 from 1973 to 2007), straw based compost (Compost, 10 Mg ha −1 yr −1), a combination of NPK + Compost, and no fertilization (control). Soil physical properties were investigated at rice harvesting stage in the 41st year for analyzing the relationship with SOC fraction. Continuous compost application increased the total SOC concentration in plough layers and improved soil physical properties. In contrast, inorganic or no fertilization markedly decreased SOC concentration resulting to a deterioration of soil physical health. Most of the SOC was the organo-mineral fraction (<0.053 mm size), accounting for over 70% of total SOC. Macro-aggregate SOC fraction (2–0.25 mm size), which is used as an indicator of soil quality rather than total SOC, covered 8–17% of total SOC. These two SOC fractions accumulated with the same tendency as the total SOC changes. Comparatively, micro-aggregate SOC (0.25–0.053 mm size), which has high correlation with physical properties, significantly decreased with time, irrespective of the inorganic fertilizers or compost application, but the mechanism of decrease is not clear. Conclusively, compost increased total SOC content and effective SOC fraction, thereby improving soil physical properties and sustaining production.

Soil physical quality as influenced by long-term fertilizer management under an intensive cropping system

The influences of long-term fertilizer management on soil organic carbon (SOC) concentration and soil physical properties were investigated under an intensive rice production system in southern China. The experiment, initiated in 1986, has f ive treatments: unfertilized, mineral fertilizer alone, rice residues plus mineral fertilizer, low manure rate plus mineral fertilizer, and high manure rate plus mineral fertilizer. The cropping system consists of barley (Hordaum vulgare L.), early rice, and late rice ( Oryza sativa L. ), three crops in a year . In May 2006, after barley harvest, soil samples were collected from the 0-10 and 10-20 cm layers to determine SOC concentration , aggregate size distribution, bulk density ( r b ), saturated hydraulic conductivity ( K s ), and water characteristic curves (SWCC). The results indicated that manure significantly reduced r b , increased SOC concentration, soil aggregation, K s , transmission and storage porosity, as well as water retention capacity. Combined application of crop residue and mineral fertilizer also improved soil physical properties, but the improvement by mineral fertilizer alone was limited. Correlation analysis demonstrated that S, the slope of the SWCC at its inflection point , was closely associated with the selected physical parameters, suggesting S was an effective parameter for soil physical quality evaluation. Nevertheless, in applying the S - theory, a unified approach to define the residual water content should be considered.