Effect of Municipal Solid Waste Compost and Farmyard Manure Application on Heavy‐Metal Uptake in Wheat

The risks related to municipal solid waste compost application in comparison to farmyard manure and mineral fertilizers on durum wheat were investigated on a short‐term experiment. Compost was applied at 40 t ha^?1 and 80 t ha^?1 with or without chemical fertilizers. Analogously, farmyard manure was applied at 40 t ha^?1. Both compost and farmyard manure improved plant growth and nutrient uptake. However, compost amendment showed more effectiveness, especially at 80 t ha^?1. Alternatively, this dose of compost involved an increase of plant copper, cadmium, and zinc concentrations in plant tissues. Metal accumulation did not thwart the enhancement of wheat yield. Furthermore, grain translocation factor reached 1 only in the case of copper; however, it showed a significant decrease following compost application (ranged between 0.57 and 0.69). Bioconcentration factor showed a significant decrease with municipal solid waste compost supply, constituting an internal detoxification mechanism.     

Assessing solid waste compost application as a practical approach for salt-affected soil reclamation

Abstract

A short-term pot experiment was made to evaluate the effectiveness of municipal solid waste compost amendment on salt-affected soil. Hordeum maritimum plants were cultivated in pots filled with a clay-loam soil containing 0 or 40 t ha^?1 of compost and irrigated with tap water at 0 or 4 g l^?1 NaCl. Soil properties and heavy metal (Zn^{2 +}, Pb^{2 +}, Cd^{2 +}) accumulation were investigated. Municipal solid waste compost application significantly increased the soil contents of carbon, nitrogen and potassium under both non-saline and saline conditions. Soil heavy metal concentrations increased substantially too, but the recorded values were below the toxicity limits. Interestingly, plants subjected to the salt–compost interaction were more vigorous, compared with those grown on non-amended soil. Altogether, our data indicate that short-term utilization of municipal solid waste compost at 40 t ha^?1 may be of potential interest in the perspective of the rehabilitation of salt-affected soils. Yet, it must be stressed that the present findings are preliminary and need to be further evaluated under field conditions before practical recommendations can be inferred.     

Effects of biochar compared to organic and inorganic fertilizers on soil quality and plant growth in a greenhouse experiment

Our contemporary society is struggling with soil degradation due to overuse and climate change. Pre‐Columbian people left behind sustainably fertile soils rich in organic matter and nutrients well known as terra preta (de Indio) by adding charred residues (biochar) together with organic and inorganic wastes such as excrements and household garbage being a model for sustainable agriculture today. This is the reason why new studies on biochar effects on ecosystem services rapidly emerge. Beneficial effects of biochar amendment on plant growth, soil nutrient content, and C storage were repeatedly observed although a number of negative effects were reported, too. In addition, there is no consensus on benefits of biochar when combined with fertilizers. Therefore, the objective of this study was to test whether biochar effects on soil quality and plant growth could be improved by addition of mineral and organic fertilizers. For this purpose, two growth periods of oat (Avena sativa L.) were studied under tropical conditions (26°C and 2600 mm annual rainfall) on an infertile sandy soil in the greenhouse in fivefold replication. Treatments comprised control (only water), mineral fertilizer (111.5 kg N ha^–1, 111.5 kg P ha^–1, and 82.9 kg K ha^–1), compost (5% by weight), biochar (5% by weight), and combinations of biochar (5% by weight) plus mineral fertilizer (111.5 kg N ha^–1, 111.5 kg P ha^–1, and 82.9 kg K ha^–1), and biochar (2.5% by weight) plus compost (2.5% by weight). Pure compost application showed highest yield during the two growth periods, followed by the biochar + compost mixture. biochar addition to mineral fertilizer significantly increased plant growth compared to mineral fertilizer alone. During the second growth period, plant yields were significantly smaller compared to the first growth period. biochar and compost additions significantly increased total organic C content during the two growth periods. Cation‐exchange capacity (CEC) could not be increased upon biochar addition while base saturation (BS) was significantly increased due to ash addition with biochar. On the other hand, compost addition significantly increased CEC. Biochar addition significantly increased soil pH but pH value was generally lower during the second growth period probably due to leaching of base cations. Biochar addition did not reduce ammonium, nitrate, and phosphate leaching during the experiment but it reduced nitrification. The overall plant growth and soil fertility decreased in the order compost > biochar + compost > mineral fertilizer + biochar > mineral fertilizer > control. Further experiments should optimize biochar–organic fertilizer systems.     

Effects of Tobacco Waste and Farmyard Manure on Soil Properties and Yield of Lettuce (Lactuca sativa L. var. capitata)

The aim of this study is to compare the effects of composted tobacco waste (CTW) with farmyard manure (FYM) on soil physical and chemical properties and yield of lettuce. This research was performed in the experimental fields of the Agriculture Faculty's research farm at Ege University in Menemen, Izmir, Turkey in 2005 and 2006. Tobacco wastes gathered from the cigarette industry were composted and applied to lettuce (Lactuca sativa L. var. capitata) with manure. Mineral fertilizers or pesticides were not applied in the experiment. The treatments were (1) control, (2) 12.5 t ha^–1 FYM + 37.5 t ha^–1 CTW, (3) 25 t ha^–1 FYM + 25 t ha^–1 CTW, (4) 50 t ha^–1 FYM, (5) 50 t ha^–1 CTW, and (6) 37.5 t ha^–1 FYM + 12.5 t ha^–1 CTW. During the experiment, soil samples were taken three times in two different periods (I, 7 September 2005; II, 11 November 2005; and III, 14 April 2006). The effects of CTW and FYM on soil physical and chemical properties and the yield were investigated. All application rates increased bulk density, field capacity, available water content, and structure stability index of soil when compared with the control. In addition, similar effects were also determined for chemical properties of soil (pH, lime content, organic matter, total soluble salt, and cation exchange capacity). Increasing rates of nitrogen, phosphorus, and potassium provided a rise in the yield. Maximum lettuce yield was 102.7 t ha^–1 at the plots where 50 t ha^–1 CTW was applied. The results show that CTW can be used as an effective soil conditioner.     

Nitrogen mineralization from mature bio‐waste compost in vineyard soils. III Simulation of soil mineral‐nitrogen dynamics

A model for nitrogen (N) dynamics in compost‐amended vineyard soils was tested for its predictive power. A soil–mineral N data set from a 3‐year field study on four different vineyard sites was used for model evaluation. The soils were treated with mature bio‐waste compost (30 and 50 Mg ha^–1 fresh matter, respectively). The model calculated soil mineral‐N contents at all sites with an overall mean bias error of –2.2 kg N ha^–1 for layers of 0.1 m thickness and an overall mean absolute error of 7.4 kg N ha^–1 layer^–1. Modeling efficiencies for the simulations of the respective treatments ranged from –0.05 to 0.41, and Willmott's Index of Agreement showed values of between 0.41 and 0.81. Acceptable model predictions as defined by the observed variability of mineral‐N contents in the respective soils ranged from 40% to 72%. A strong increase in soil mineral‐N concentration following the compost application at all sites could not be reproduced with the model, thereby reducing the prediction accuracy significantly. The model performance confirms that previously derived N‐mineralization parameters are suitable to describe the N release from soil‐applied mature bio‐waste compost under the environmental conditions of vineyards in Germany.     

Changes in Biological Properties in Soil Amended with Rock Phosphate and Waste Mica Enriched Compost using Biological Amendments and Chemical Fertilizers Under Wheat-Soybean Rotation

The main aim of this research work is to prepare an enriched compost using rice straw mixed with rock phosphate, waste mica and Aspergillus awamori and to study their effect on changes in microbial properties in soils with and without chemical fertilizers under wheat-soybean rotation. Data revealed that significant increase in microbial biomass carbon (MBC), dehydrogenase activity, phosphatase activities, and microbial biomass phosphorus (MBP) in soil were maintained in enriched compost than ordinary compost after both the crops. Significant increase in MBC, dehydrogenase activity, phosphatase activities, and MBP were found in surface soil. The maximum microbial activities were observed in the treatment receiving 50% recommended dose of fertilizer (RDF) + enriched compost at 5 t ha^?1 indicating that integrated use of chemical fertilizers and enriched compost significantly improved the biological properties of soil under wheat–soybean rotation thereby enhanced soil fertility and crop production.     

Long-term effects of heavy metals from composted municipal waste on some enzyme activities in a cultivated soil

A 3-year field experiment on a calcareous Fluventic Xerochrept planted with corn (Zea mays L.) was carried out to evaluate the effects of amending the soil with high and low rates of composted municipal waste on soil enzyme activities (alkaline phosphomonoesterase, phosphodiesterase, arylsulphatase, dehydrogenase, and l-asparaginase). These enzyme activities all increased when compost was added at rates of up to 90 t ha^-1, and the phosphatases continued to show a linear increase with compost rates of up to 270 t ha^-1. The addition of mineral fertilizer increased enzyme activities in unamended soil, and masked the stimulating effect of compost on the amended soils. Heavy metals did not affect soil enzyme activities up to a compost addition of at least three times the amount specified by Italian law.     

RESPONSE OF TURFGRASS GROWTH IN A BLACK CHERNOZEMIC SOIL AMENDED WITH MUNICIPAL SOLID/BIOSOLID WASTE COMPOST

High transportation cost is a barrier which prevents land application of compost far away from where the compost is produced. As a result, use of compost in lawns is becoming a popular alternative in municipalities where compost is produced from municipal solid/biosolid waste. A four-year (2002 to 2005) field experiment was conducted on turfgrass [20% Kentucky Blue (Poa pratensis L.) + 80% Creeping Red Fescues (Festuca rubra L.)] grown on a Black Chernozem soil near Edmonton, Alberta, Canada, to determine the effect of rate and frequency of spring application of compost (prepared from soild/biosolid waste of city of Edmonton) on biomass, sward color, concentration and uptake of nutrients of sward, and soil chemical properties. There were three compost treatments: 50 Mg ha^?1 annual; 100 Mg ha^?1 (1st year) + 50 Mg ha^?1 (2nd year) split, and 150 Mg ha^?1 once in three years (2002, 2003 and 2004) applications. In addition, there were check (no fertilizers or compost) and annual nitrogen-phosphorus-potassium-sulfur (NPKS) fertilizer application (100 kg N + 20 kg P + 42 kg K + 20 kg S ha^?1 annual) treatments. In the fourth year (2005), residual effect of applied compost on turfgrass growth was determined. Annual application of compost at 50 Mg ha^?1 had more green color of leaf, and higher sward N concentration and biomass production of turfgrass for prolonged periods than the check treatment. In comparison with annual application, high initial compost and split applications generated greater turfgrass growth only in the first two years, but produced higher cumulative biomass over the three- or four-year period. Both annual and cumulative biomass yields were highest in treatments receiving NPKS fertilizers. After four growing seasons, there was no residual mineral N in soil from both compost and NPKS fertilizer, and no residual sulfate-S in soil from NPKS fertilizer treatments. The amounts of extractable P and exchangeable K in soil were greater in compost treatments than in the NPKS fertilizer treatment. There was downward movement of extractable P into the 15–30 cm soil depth in one-time initial and split compost and NPKS fertilizer treatments, and of sulfate-S in all compost treatments. In conclusion, annual application of compost in spring at 50 Mg ha^?1 is recommended for sustainable color and growth of turfgrass.     

Effect of organic and inorganic sources of nutrients on yield,economics, and energetics of pepper and soil properties in naturally ventilated polyhouse

A field experiment was conducted during the summer season of 2009 and 2010 at Vivekananda Parvatiya Krishi Anusandhan Sansthan, Hawalbagh, Almora, Uttarakhand, under the mid-hills of north-western Himalaya, to study the effect of farmyard manure and fertilizers on fruit yield, economics, energetics of pepper (Capsicum annuum L.) and on soil chemical properties. The highest level of farmyard manure (20 t ha^?1) along with 125% of recommended NPK (125, 27.5, and 52.1 kg N, P and K ha^?1) resulted in significantly higher fruit yield (33.9 t ha^?1) over other combinations. Both farmyard manure and inorganic fertilizers significantly increased fruits/plant, average fruit weight, plant height, fruit length, and fruit diameter. The maximum net returns (4520 $ ha^?1) was achieved at 20 t of FYM along with 125% of recommended NPK. Energy ratio of 1.29 and 1.13 was the highest under 20 t FYM ha^?1 and 125% of recommended NPK, respectively. Available nutrients (N, P, and K) improved the status of the soil significantly due to 20 t ha^?1 of FYM and 125% of recommended NPK over other treatments.     

Application rate and composting method affect the immediate and residual manure fertilizer value in a maize–rice–rice–maize cropping sequence on a degraded soil in northern Vietnam

A field experiment was carried out in northern Vietnam to investigate the effects of adding different additives [rice (Oriza sativa L.) straw only, or rice straw with added lime, superphosphate (SSP), urea or a mixture of selected microorganism species] on nitrogen (N) losses and nutrient concentrations in manure composts. The composts and fresh manure were applied to a three-crop per year sequence (maize–rice–rice) on a degraded soil (Plinthic Acrisol/Plinthaquult) to investigate the effects of manure type on crop yield, N uptake and fertilizer value. Total N losses during composting with SSP were 20% of initial total N, while with other additives they were 30–35%. With SSP as a compost additive, 65–85% of the initial ammonium-N (NH₄-N) in the manure remained in the compost compared with 25% for microorganisms and 30% for lime. Nitrogen uptake efficiency (NUE) of fresh manure was lower than that of composted manure when applied to maize (Zea mays L.), but higher when applied to rice (Oriza sativa L.). The NUE of compost with SSP was generally higher than that of compost with straw only and lime. The mineral fertilizer equivalent (MFE) of manure types for maize decreased in the order: manure composted with SSP?>?manure composted with straw only and fresh manure?>?manure composted with lime. For rice, the corresponding order was: fresh manure?>?manure composted with SSP/microorganisms/urea?>?manure composted with lime/with straw alone. The MFE was higher when 5 tons manure ha^?1 were applied than when 10 tons manure ha^?1 were applied throughout the crop sequence. The residual effect of composted manures (determined in a fourth crop, with no manure applied) was generally 50% higher than that of fresh manure after one year of manure and compost application. Thus, addition of SSP during composting improved the field fertilizer value of composted pig manure the most.     

Potential of mine land reclamation for soil organic carbon sequestration in Ohio

Soils are an effective sink for carbon storage and immobilization through biomass productivity and enhancement of soil organic carbon (SOC) pool. The SOC sink capacity depends on land use and management. Degraded lands lose large amounts of C through SOC decomposition, erosion, and leaching. Thus, restoration of disturbed and degraded mine lands can lead to increase in biomass productivity, improved soil quality and SOC enhancement and sequestration. Reclamation of mined lands is an aggrading process and offers significant potential to sequester C. A chronosequence study consisting of 0‐, 5‐, 10‐, 15‐, 20‐ and 25‐year‐old reclaimed mine soils in Ohio was initiated to assess the rate of C sequestration by pasture and forest establishment. Undisturbed pasture and forest were used as controls. The SOC pool of reclaimed pasture sites increased from 15·3 Mg ha⁻¹ to 44·4 Mg ha⁻¹ for 0–15 cm depth and from 10·8 Mg ha⁻¹ to 18·3 Mg ha⁻¹ for 15–30 cm depth over the period of 25 years. The SOC pool of reclaimed forest sites increased from 12·7 Mg ha⁻¹ to 45·3 Mg ha⁻¹ for 0–15 cm depth and from 9·1 Mg ha⁻¹ to 13·6 Mg ha⁻¹ for 15–30 cm depth over the same time period. The SOC pool of the pasture site stabilized earlier than that of the forest site which had not yet attained equilibrium. The SOC sequestered in 0–30 cm depth over 25 years was 36·7 Mg ha⁻¹ for pasture and 37·1 Mg ha⁻¹ for forest. Copyright © 2000 John Wiley & Sons, Ltd.     

Effects of Long-Term Fertilizer Application and Rainfall Distribution on Cotton Productivity,Profitability, and Soil Fertility in a Semi-arid Vertisol

Long-term fertilizer experiments were conducted on cotton (Gossypium hirsutum) for 21 years with eight fertilizer treatments in a fixed site during 1987–2007 to identify an efficient treatment to ensure maximum yield, greater sustainability, monetary returns, rainwater-use efficiency, and soil fertility over years. The results indicated that the yield was significantly influenced by fertilizer treatments in all years except 1987 1988, and 1994. The mean cotton yield ranged from 492 kg ha^?1 under the control to 805 kg ha^?1 under 25 kg nitrogen (N) [farmyard manure (FYM)] + 25 kg N (urea) + 25 kg phosphorus (P) ha^?1. Among the nutrients, soil N buildup was observed with all treatments, whereas application of 25 kg N + 12.5 kg P ha^?1 exhibited increase in P status. Interestingly, depletion of potassium (K) was recorded under all the fertilizer treatments as there was no K application in any of the treatments. An increase in soil N and P increased the plant N and P uptake respectively. Using relationships of different variables, principal component (PC) analysis technique was used for assessing the efficiency of treatments. In all the treatments, five PCs were found significant that explained the variability in the data of variables. The PC model of 25 kg N (FYM) + 25 kg N (urea) + 25 kg P ha^?1 explained maximum variability of 79.6% compared to other treatments. The treatment-wise PC scores were determined and used in developing yield prediction models and measurement of sustainability yield index (SYI). The SYI ranged from 44.4% in control to 72.7% in 25 kg N (FYM) + 25 kg N (urea) + 25 kg P ha^?1, which attained a mean cotton yield of 805 kg ha^?1 over years. Application of 25 kg N (FYM) + 25 kg N (urea) + 25 kg P ha^?1 was significantly superior in recording maximum rainwater-use efficiency (1.13 kg ha^?1 mm^?1) and SYI (30.5%). This treatment also gave maximum gross returns of Rs. 30272 ha^?1 with benefit–cost ratio of 1.60 and maintained maximum organic carbon and available N, P, and K in soil over years. These findings are extendable to cotton grown under similar soil and agroclimatic conditions in any part of the world.     

Effects of Land Management on Different Forms of Soil Carbon in Olive Groves in Mediterranean Areas

This study analyses soil organic carbon (SOC) and hot‐water extractable carbon, both measures of soil quality, under different land management—(i) conventional tillage (CT); (ii) CT plus the addition of oil mill waste alperujo (A); (iii) CT plus the addition of oil mill waste olive leaves (L); (iv) no tillage with chipped pruned branches (NT₁); and (v) no tillage with chipped pruned branches and weeds (NT₂)—in a typical Mediterranean agricultural area: the olive groves of Andalusia, southern Spain. SOC values in CT, A, NT₁ and NT₂ decreased with depth, but in NT₂, the surface horizon (0–5 cm) had higher values than the other treatments, 47% more than the average values in the other three soils. In L, SOC also decreased with depth, although there was an increase of 88·5% from the first (0–10 cm) to the second horizon (10–16 cm). Total SOC stock values were very similar under A (101·9 Mg ha⁻¹), CT (101·7 Mg ha⁻¹), NT₁ (105·8 Mg ha⁻¹) and NT₂ (111·3 Mg ha⁻¹, if we consider the same depth of the others). However, SOC under L was significantly higher (p < 0·05) at 250·2 Mg ha⁻¹. Hot‐water extractable carbon decreased with depth in A, CT and NT₁. NT₂ and L followed the same pattern as the other management types but with a higher value in the surface horizon (2·3 and 4·9 mg g⁻¹, respectively). Overall, our results indicate that application of oil mill waste olive leaves under CT (L) is a good management practice to improve SOC and reduce waste. Copyright © 2014 John Wiley & Sons, Ltd.     

Nitrogen Availability Seven Years After a High-Rate Food Waste Compost Application

Long-term effects of compost application are expected, but rarely measured. A 7-yr growth trial was conducted to determine nitrogen availability following a one-time compost application. Six food waste composts were produced in a pilot-scale project using two composting methods (aerated static pile and aerated, turned windrow), and three bulking agents (yard trimmings, yard trimmings + mixed paper waste, and wood waste + sawdust). For the growth trial, composts were incorporated into the top 8 to 10 cm of a sandy loam soil at application rates of approximately 155 Mg ha^?1 (about 7 yd³ 1000 ft²). Tall fescue (Festuca arundinacea Schreb. ‘A.U. Triumph’) was seeded after compost incorporation, and was harvested 40 times over a 7-yr period. Grass yield and grass N uptake for the compost treatments was greater than that produced without compost at the same fertilizer N rate. The one-time compost application increased grass N uptake by a total of 294 to 527 kg ha^?1 during the 7-yr. field experiment. The greatest grass yield response to compost application occurred during the second and third years after compost application, when annual grass N uptake was increased by 93 to 114 kg ha^?1 yr^?1. Grass yield response to the one-time compost application continued at about the same level for Years 4 through 7, increasing grass N uptake by 42 to 62 kg ha^?1 yr^?1. Soil mineralizable N tests done at 3 and 6 yr. after application also demonstrated higher N availability with compost. The increase in grass N uptake accounted for 15 to 20% of compost N applied after 7-yr. for food waste composts produced with any of the bulking agents. After 7-yr, increased soil organic matter (total soil C and N) in the compost-amended soil accounted for approximately 18% of compost-C and 33% of compost-N applied. This study confirmed the long-term value of compost amendment for supplying slow-release N for crop growth.     

Long‐term effects of fertilization on some soil properties under rainfed soybean‐wheat cropping in the Indian Himalayas

This study aims to examine the effects of long‐term fertilization and cropping on some chemical and microbiological properties of the soil in a 32 y old long‐term fertility experiment at Almora (Himalayan region, India) under rainfed soybean‐wheat rotation. Continuous annual application of recommended doses of chemical fertilizer and 10 Mg ha^–1 FYM on fresh‐weight basis (NPK + FYM) to soybean (Glycine max L.) sustained not only higher productivity of soybean and residual wheat (Triticum aestivum L.) crop, but also resulted in build‐up of total soil organic C (SOC), total soil N, P, and K. Concentration of SOC increased by 40% and 70% in the NPK + FYM–treated plots as compared to NPK (43.1 Mg C ha^–1) and unfertilized control plots (35.5 Mg C ha^–1), respectively. Average annual contribution of C input from soybean was 29% and that from wheat was 24% of the harvestable aboveground biomass yield. Annual gross C input and annual rate of total SOC enrichment from initial soil in the 0–15 cm layer were 4362 and 333 kg C ha^–1, respectively, for the plots under NPK + FYM. It was observed that the soils under the unfertilized control, NK and N + FYM treatments, suffered a net annual loss of 5.1, 5.2, and 15.8 kg P ha^–1, respectively, whereas the soils under NP, NPK, and NPK + FYM had net annual gains of 25.3, 18.8, and 16.4 kg P ha^–1, respectively. There was net negative K balance in all the treatments ranging from 6.9 kg ha^–1 y^–1 in NK to 82.4 kg ha^–1 y^–1 in N + FYM–treated plots. The application of NPK + FYM also recorded the highest levels of soil microbial‐biomass C, soil microbial‐biomass N, populations of viable and culturable soil microbes.     

Effect of distillery effluents on plant and soil enzymatic activities and groundnut quality

A field experiment was conducted during the rainy season 2000 to examine the effect of distillery effluents, i.e., biomethanated spent wash (BSW), raw spent wash (RSW), and lagoon sludge (LS) versus recommended NPK+FYM (farmyard manure) on nutritional quality of groundnut (Arachis hypogaea L.) and enzyme activities of plant and soil. The distillery effluents did not affect the oil content (%), crude and true protein contents (%) in groundnut but increased the seed yield and the contents of methionine by 44 % (1.15 g (16 g N)^–1 vs. 0.80 g (16 g N)^–1 in control) and of cysteine by 24 % (1.36 g (16 g N)^–1 vs. 1.10 g (16 g N)^–1 in control). BSW produced the highest seed yield (619 kg ha^–1) followed by RSW (557 kg ha^–1) and LS (472 kg ha^–1). LS recorded the highest total chlorophyll content (2.94 mg (g FW)^–1) in groundnut leaves. Application of BSW and RSW significantly increased the activity of plant peroxidase whereas the plant polyphenol oxidase was higher in BSW only. The application of distillery effluents did not affect the nitrate reductase activity but BSW significantly increased the nitrate content in the rhizosphere soil. The three effluents significantly increased the dehydrogenase and alkaline phosphatase activity more than recommended NPK+FYM.     

CARBON BUDGET AND SEQUESTRATION POTENTIAL IN A SANDY SOIL TREATED WITH COMPOST

The effects of compost application on soil carbon sequestration potential and carbon budget of a tropical sandy soil was studied. Greenhouse gas emissions from soil surface and agricultural inputs (fertiliser and fossil fuel uses) were evaluated. The origin of soil organic carbon was identified by using stable carbon isotope. The CO₂, CH₄ and N₂O emissions from soil were estimated in hill evergreen forest (NF) plot as reference, and in the corn cultivation plots with compost application rate at 30 Mg ha⁻¹ y⁻¹ (LC), and at 50 Mg ha⁻¹ y⁻¹ (HC). The total C emissions from soil surface were 8·54, 10·14 and 9·86 Mg C ha⁻¹ y⁻¹ for NF, HC and LC soils, respectively. Total N₂O emissions from HC and LC plots (2·56 and 3·47 kg N₂O ha⁻¹ y⁻¹) were significantly higher than from the NF plot (1·47 kg N₂O ha⁻¹ y⁻¹). Total CO₂ emissions from fuel uses of fertiliser, irrigation and machinery were about 10 per cent of total CO₂ emissions. For soil carbon storage, since 1983, it has been increased significantly (12 Mg ha⁻¹) under the application of 50 Mg ha⁻¹ y⁻¹ of compost but not with 30 Mg ha⁻¹ y⁻¹. The net C budget when balancing out carbon inputs and outputs from soil for NF, HC and LC soils were +3·24, −2·50 and +2·07 Mg C ha⁻¹ y⁻¹, respectively. Stable isotope of carbon (δ¹³C value) indicates that most of the increased soil carbon is derived from the compost inputs and/or corn biomass. Copyright © 2011 John Wiley & Sons, Ltd.     

Soil Quality Assessment under Restorative Soil Management Practices in Soybean (Glycine Max) after Six Years in Semi-Arid Tropical Black Lands of Central India

Vertisol soils of central India are heavy in texture, with high clay content and low organic matter. These soils are prone to degradation and the soil loss is due to poor management practices including excessive tillage. Based on a long-term study conducted for improving the quality of these soils, it was found that management practice such as low tillage (LT) + 4 t ha^?1 compost + herbicide (Hb) recorded significantly higher organic carbon (OC) (6.22 g kg^?1) and available N (188.5 kg ha^?1) compared to conventional tillage (CT) + recommended fertilizer (RF) + off-season tillage (OT) + hand weeding (HW) (OC: 4.71 g kg^?1, available nitrogen (N) (159.3 kg ha^?1). Among the physical soil quality parameters, mean weight diameter (MWD) was significantly higher under LT + 4 t ha^?1 straw + Hb (0.59 mm). The practice of LT + 4 t ha^?1 straw + HW recorded significantly higher microbial biomass carbon (MBC) (388.8 μg g^?1). The order of key indicators and their contribution towards soil quality was as follows: OC (29%) >, MBC (27%) > available zinc (Zn) (22%) > MWD (9%) > available boron (B) (8%), > dehydrogenase activity (DHA) (5%). The order of the best treatment which maintained soil quality index (SQI) values reasonably good (>1.5) was as follows: LT + 4t ha^?1 compost + HW (1.65) > LT + 4 t ha^?1 compost +Hb (1.60) > LT + 4t ha^?1 straw + HW (1.50). Hence, these treatments could be recommended to the farmers for maintaining higher soil quality in Vertisols under soybean system. Correlation studies revealed stronger relationship between key indicators like OC (R² = 0.627), MBC (R² = 0.884), available Zn (R² = 0.739) and DHA (R² = 0.604) with Relative Soil Quality Index (RSQI). The results of the present study would be highly useful to the researchers, farmers and land managers.     

Modeling Effects of Soil Fertility of Nutrients and Precipitation of 22 Years on Sustainable Productivity and Profitability of Pearlmillet and Sorghum Rotation in Semi-arid Vertisols

Based on experiments conducted during 1988–2009 on rainfed pearl millet/sorghum with 9 treatments in Vertisols, an efficient treatment for sustainable productivity is identified. Twenty kg of nitrogen (N) from farmyard manure (FYM) + 20 kg N (urea) + 10 kg phosphorus (P) ha^?1 in pearl millet and 40 kg N (urea) + 20 kg P + 25 kg zinc sulfate (ZnSO₄) ha^?1 in sorghum gave maximum yield and rainwater-use efficiency, whereas 20 kg N (FYM) + 20 kg (urea) + 10 kg P ha^?1 in pearl millet and 40 kg (urea) + 20 kg P ha^?1 in sorghum and gave maximum soil N, P, and potassium (K) over years. The regression model of 20 kg N (crop residue) + 20 kg N (urea) + 10 kg P ha^?1 gave maximum R² for predicting sorghum equivalent yield separately through precipitation and soil variables, whereas 20 kg N (FYM) + 20 kg N (urea) + 10 kg P ha^?1 gave maximum R² under combined model of both variables. Treatment of 20 kg N (FYM) + 20 kg N (urea) + 10 kg P ha^?1 was superior for attaining maximum sorghum equivalent yield of 1062 kg ha^?1, net returns of Rs. 4805 ha^?1, benefit/cost (BC) ratio of 1.50, and 127 kg ha^?1 of soil N, 10.3 kg ha^?1 of soil P, and 386 kg ha^?1 of soil K over years.     

Thirteen years of continued application of composted organic wastes in a vineyard modify soil quality characteristics

A solution for environmentally wiser agriculture is the use of composted organic wastes as soil amendments. Just as this alleviates the problem of recycling organic residues, it provides necessary nutrient input for food production. The objective of this work was to study the effect that 13 years of applying three different composted organic wastes or organic amendments have had on soil quality, GHG emissions and the dynamics of its microbial communities 15 days after the annual application. For this purpose, in 1996 a field trial was set up in a Tempranillo vineyard. Since 1998, the applied organic amendments have been as follows: 1. a pelletized organic compost (PEL) made from plant, animal and sewage sludge residues; 2. a compost made from the organic fraction of municipal solid waste (OF-MSW); 3. a compost made of stabilized sheep manure (SMC); 4. a mineral fertilizer (NPK); and 5. an unaltered control. The mean annual doses applied since 1998 have been 3700 kg ha⁻¹ fresh weight (FW) of PEL, 4075 kg ha⁻¹ FW of OF-MSW, 4630 kg ha⁻¹ FW of SMC, and 340 kg ha⁻¹ of NPK treatment. Soil quality was consistently enhanced by amendment application over the 13 years. Total nitrogen was significantly increased in PEL (0.1%), OF-MSW (0.09%) and SMC (0.1%) compared to control (0.06%). Nutrient content was also improved in a similar way, e.g. the most significant increase in P Olsen (80.7 mg kg⁻¹) and K₂O (473.8 mg kg⁻¹) was found on SMC. The overall enzyme activity was also increased 15 days after the annual application and OF-MSW had the highest rate (95.9) compared to control (51.3). This increase in metabolic activity was also recorded in GHG emissions. CO₂ equivalents per hectare were 1745 kg for OF-MSW and it was the only significant difference found. PEL with 1598 kg and SMC with 1591 kg were not different from the Control (1104 kg). Even though GHG emissions in the soil increased because of the application, soil organic matter content increased significantly (at least 35% more in all organic treatments compared to control) and this rise in organic matter was consistent over the years. According to the results, 85% of the sequences corresponded to 5 main phyla: Proteobacteria, Actinobacteria, Bacteroidetes, Acidobacteria and Gemmatimonadetes, with unclassified material making up for 10.9% (average) of the sequences. Bacterial diversity by Shannon and Chao1 indices was not affected 15 days after the application. However, slight changes in the bacterial community were recorded 15 days after application only in OF-MSW treatment. Assessing soil quality using these three factors allows the relevant agronomical capabilities of the soil to be integrated with the potential effect of this practise on global warming.