Comparison of N Mineralization Rate and Pattern in Different Manure- and Sewage Sludge-Amended Calcareous Soil

A 12-week incubation experiment was conducted to determine the pattern and rate of N mineralized from organic materials. Treatments consisted of sheep manure (SM), cattle manure (CM), poultry manure (PM), sewage sludge (SS) at 1% (W/W) level, and unfertilized treatment with three replications. The concentrations of nitrate (NO₃)- nitrogen (N) and ammonium (NH₄)-N were determined in day 1 and 1, 2, 4, 8, and 12 weeks after the beginning of incubation. Results indicated that the magnitude of N mineralized during the incubation time periods was in the order of CM (134 mg kg^?1) > PM (83 mg kg^?1) > SS (56 mg kg^?1) > SM (55 mg kg^?1), and different management is required for obtaining optimum N-use efficiency. In conclusion, improving N-uptake efficiency in manure- and SS-amended soils depends on the pattern and rate of N mineralization to synchronize N released with crop N demand periods.     

Phosphorus Source Effects on Soil Organic Phosphorus: A 31P NMR Study

The nature of organic phosphorus (P_o) in animal waste and in soil is important from both plant nutrition and environmental perspectives. The objectives of this study were (1) to monitor the nature of P_o in different animal wastes and biosolids using solution state ³¹P NMR spectroscopy and (2) to understand the nature of P_o as affected by crop P removal in soil amended with different animal wastes and biosolids under greenhouse conditions. Two types of stockpiled cattle (Bos taurus) manure (CM1 and CM2), solid turkey (Meleagris gallopava) litter (TL), solid hog (Sus scrofa) manure (HM), and aerobically digested biosolids (SS) were used. Two kg of Wabash silt loam soil was amended with 0 or 150 mg P kg^?1 from the P sources. Seven harvests of corn (Zea mays L.) were collected, each 35 days after sowing. Organic P was extracted with 0.4 M NaOH from soil samples collected before cropping and after the seventh harvest, as well as from each P source. ³¹P NMR analysis suggested that sugar phosphomonoester was present in all P sources and was the dominant constituent of both CM1 and CM2. Phosphomonoester was detected in large amounts in TL, HM, and SS. Prior to crop P removal, the application of all P sources caused the relative content of sugar phosphomonoester to be greater than the control. Crop P removal resulted in reductions in the relative content of sugar phosphodiesters and phosphodiester in CM1‐ and CM2‐amended soils, respectively. Phosphomonoester was also decreased in TL‐, HM‐, and SS‐amended soils in response to cropping.     

Management options to decrease phosphorus and sediment losses from irrigated cropland grazed by cattle and sheep

In southern New Zealand, grazing of forage crops is common practice to satisfy feed requirements of animals in winter when pasture growth is limited. This practice has been shown to cause soil physical damage and increased loss of surface water contaminants sediment and phosphorus (P) to water bodies. Strategies to mitigate the loss of sediment and P were trialled on a Pallic soil type (Aeric Fragiaquept) in the North Otago Rolling Downlands of New Zealand. All sites were irrigated and measurements were made of losses in overland and sub‐surface flow from intensive cattle or sheep grazed, winter forage crops, and sheep grazed pasture. Two mitigations (restricted grazing of crop to three hours and the application of aluminium sulphate) were assessed for their potential to decrease contaminant loss from cropland. Volumes of surface runoff and loss of total P, filterable reactive P and sediment showed significant differences (P < 0.05) between the control treatments (i.e. no mitigation) with cattle crop (88 mm surface runoff) > sheep crop (67 mm) > sheep pasture (33 mm). The contribution of irrigation water to overland flow water, as a result of saturation‐excess conditions, varied between treatments with more loss under cattle crop (20% of total) compared with sheep crop (15%) and sheep pasture (11%). These differences are probably an effect of soil physical condition and highlight the importance of accurate irrigation scheduling to keep soil moisture below field capacity. Restricted winter grazing and alum application after grazing significantly (P < 0.05) decreased P losses in surface runoff under cattle (from 1.4 to 0.9 kg P/ha) and sheep (from 1.0 to 0.7 kg/P/ha) grazed crop plots by about 30%. In cattle grazed plots, restricted grazing also decreased suspended sediments (SS) by 60%. The use of restricted grazing is suggested as a means of decreasing P and SS loss from grazed winter forage crops. The use of alum shows some promise for decreasing P losses, but requires further work to determine its long‐term effectiveness and use in other soils and management regimes.     

Source areas of phosphorus transfer in an agricultural catchment,south-eastern Norway

Abstract

The strategy to mitigate phosphorus (P) losses in areas of arable cropping in Norway has focused on measures to reduce erosion. Risk assessment of erosion has formed the basis for implementation of the measures. The soil P content has increased during recent decades, motivating an evaluation of its effect on P transfer in the landscape. The present study describes the spatial variability of runoff P concentrations from an agricultural dominated catchment (4.5 km²), representative for agriculture in south-eastern Norway. The concentrations of suspended sediments (SS), total P (TP) and dissolved reactive P (DRP) in runoff from 22 subcatchments (0.3–263 ha) during one year (monthly and during runoff-events) were evaluated. Contributions from point sources were 38 kg TP yr^?1 compared to a total P loss of 685 kg yr^?1 from the whole catchment. During low flow, mean diffuse TP concentration in runoff from subcatchments varied from 28 to 382 µg l^?1. The mean low flow TP concentration was 39 µg l^?1 from the housing area (only diffuse runoff) and 33 µg l^?1 from the forested area. During high flow the highest diffuse TP concentration was measured in an area with high erosion risk and high soil P status. At the subcatchment level the transfer of SS varied from 25 to 175% of the whole catchment SS transfer. Correspondingly for TP, the transfer varied from 50 to 260% of the whole catchment TP transfer. For each of five agricultural subcatchments the slope of the relationship between TP and SS concentrations reflected the mean soil P status of the subcatchment. Erosion risk estimates were closely related to the SS concentration (R²=0.83). The study illustrates that soil P status in addition to soil erosion is an important factor for P transfer.     

Expression of Soil Chemical and Biological Behavior on Nutritional Quality of Aromatic Rice as Influenced by Organic and Mineral Fertilization

The aim of the study was to evaluate changes in the yield and nutritional characteristics of aromatic rice as influenced by organic versus mineral fertilization. Aromatic rice was grown on four levels of cattle manure (CM; 5, 10, 15, and 20 Mg ha^?1). Other treatments were equivalent amounts of nitrogen (N), phosphorus (P), and potassium (K) in different levels of manure fertilizer and mineral fertilizer. After 6 years of cropping, organically managed plots were superior to mineral-fertilized plots in terms of grain yields of rice at 5, 10, and 15 Mg ha^?1. Cattle manure at 20 Mg ha^?1 and its equivalent NPK through mineral-fertilizer treatment provided 41.1% and 37.9% increases in average grain yield (5.2 and 5.1 Mg ha^?1) over the unamended control. Protein content was greater in mineral-fertilized rice grains at all levels of CM. Soil dehydrogenase, β-glucosidae, urease, and acid phosphatase activities were greater in soil treated with CM than soil treated with the corresponding mineral fertilizer at all levels. There was buildup of soil-available N, K, and iron (Fe) in soils treated with CM. Grain hardness increased with increasing rates of nutrient application for both mineral-fertilized and organically grown rice; in contrast, amylose content was lower in treatments receiving more nutrients, irrespective of nutrient sources. In terms of functional property, phenol content in rice grain increased with increasing nutrient supply. Potassium and Fe contents were more in CM-treated rice than in mineral-fertilized treatments at greater rates of application. Results suggest that after building up the soil nutrient status, comparable yield and better nutritional and functional qualities of rice can be achieved in organically managed soils than in mineral-fertilized soils.     

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.     

Effects of long-term application of various organic amendments on soil particulate organic matter storage and chemical stabilisation of vertisol soil

Current understanding of the effects of long-term application of various organic amendments on soil particulate organic matter (POM) storage and chemical stabilisation remains limited. Therefore, we collected soil samples from the soil profile (0–100?cm) under six treatments in a 31-year long-term fertilisation experiment: no fertiliser (CK), mineral fertilisers (NPK), mineral fertilisers plus 3.8 or 7.5?t?ha^?1?year^?1 (fresh base) the amount of wheat straw (1/2SNPK and SNPK) and mineral fertilisers plus swine or cattle manure (PMNPK and CMNPK). Long-term incorporation of wheat straw and livestock manure amendments significantly (p?<?0.05) increased crop yield and sustainable yield index, and POM storage compared with CK and NPK treatments. The mole ratios of H/C in the POM under organic amendment treatments significantly (p?<?0.05) decreased by 13.8% and 37.1%, respectively, compared with the NPK treatment. Similarly, solid state NMR spectroscopy showed that the O–alkyl carbon content of POM was greatly decreased, whereas aromatic carbon contents and alkyl to O–alkyl carbon ratios were substantially increased under PMNPK and CMNPK treatments. In conclusion, we recommend long-term livestock manure application as a preferred strategy for enhancing POM quantity and quality (chemical stability), and crop yield of vertisol soil in northern China.     

Agronomic Evaluation of Phosphorus Sources in Lowland Rice Production

Phosphorus (P) deficiency is one of the most yield-limiting factors in lowland rice production on Brazilian Inceptisol. The objective of this study was to evaluate eight P sources for lowland rice production. The P sources were simple superphosphate (SSP), polymer-coated simple superphosphate (PSSP), ammoniated simple superphosphate (ASSP), polymer-coated ammoniated simple superphosphate (PASSP), triple superphosphate (TSP), polymer-coated triple superphosphate (PTSP), monoammonium phosphate (MAP), and polymer-coated monoammonium phosphate (PMAP). These P sources were applied in four rates (i.e., 50, 100 200, and 400 mg P kg^?1) + one control treatment (0 mg P kg^?1). Plant height, straw yield, grain yield, panicle number, and root dry weight were significantly increased in a quadratic fashion with increasing P levels from 0 to 400 mg kg^?1 of all the P sources evaluated. However, overall maximum root length and P-use efficiency were significantly less at greater P levels. Based on regression equation, maximum plant height was obtained with 262 mg P kg, maximum straw yield was obtained with 263 mg P kg^?1, maximum grain yield was obtained with 273 mg P kg^?1, and maximum panicle density was obtained with 273 mg P kg^?1. Plant growth and yield components had significant positive association with grain yield, except maximum root length. Based on grain yield and average P rate of maximum grain yield, which is 273 mg kg^?1, P sources were classified for P-use efficiency in the order of PSSP = TSP > PTSP > PASSP > SSP > MAP > ASSP. Soil chemical properties [pH; P; potassium (K); calcium (Ca); magnesium (Mg); hydrogen (H) + aluminum (Al); cation exchange capacity (CEC); base saturation; Ca, Mg, and K saturation; acidity saturation; Ca/Mg, Ca/K, and Mg/K ratios] changed significantly with the addition of different P treatments.     

Comparative Efficiency of Phosphorus Sources for Upland Rice Production

Rice (Oryza sativa L.) is a staple food for more than 50% of the world’s population, and phosphorus (P) is one of the most yield-limiting nutrients for rice production in tropical acidic soils worldwide. A greenhouse experiment was conducted to evaluate efficiency of six P sources for upland rice production. The P sources used were simple superphosphate (SSP), polymer-coated SSP (PSSP), triple superphosphate (TSP), polymer-coated TSP (PTSP), monoammonium phosphate (MAP), and polymer-coated MAP (PMAP). There were four P rates [50, 100 200, and 400 mg phosphorus (P) kg^?1] applied with four sources plus one control treatment [0 mg phosphorus (P) kg^?1]. Plant height, straw yield, grain yield, panicle density, root dry weight, maximum root length, and 1000-grain weight were significantly increased with increasing P rates in the range of 0 to 400 mg P kg^?1. However, P-use efficiency (mg grain produced per mg P applied) was decreased with increasing P rate. Based on regression equation, overall maximum plant height was obtained with the application of 235 mg P kg^?1, maximum straw yield with the application of 265 mg P kg^?1, and maximum grain yield at 227 mg P kg^?1. Based on maximum grain yield, the P source were classified as PMAP > SSP = MAP > PSSP > TSP > PTSP in the upland rice production efficiency. Overall, maximum panicle density was obtained with the addition of 231 mg P kg^?1 and maximum 1000-weight was obtained with the addition of 226 mg P kg^?1. Similarly, overall root dry weight and maximum root length were achieved with the application of 261 and 298 mg P kg^?1 of soil. Most of the growth and yield components had a significant positive association with grain yield. Optimum soil acidity indices such as pH; exchangeable calcium (Ca), magnesium (Mg), and potassium (K); Ca, Mg, and K saturation; base saturation; and acidity saturation were established for maximum upland rice grain yield.     

Variation in Phosphorus Uptake and Use Efficiencies Between Pigeonpea Genotypes and Cowpea

ABSTRACT

Low bioavailability of soil phosphorus (P) often limits N₂ (nitrogen) fixation and crop production in large parts of the tropics. The efficiency of P acquisition and P use by 21 genotypes of pigeonpea [Cajanus cajan (L.) Millsp.] were studied in a pot experiment using two cowpea [Vigna unguiculata (L.) Waip.] genotypes as controls. The short-duration genotypes produced more dry matter, accumulated more P, and produced more dry matter per unit of absorbed P than the medium-and long-duration genotypes. Dry-matter production correlated positively with the P uptake (r² = 0.72) and P-use efficiency (r² = 0.86). The P uptake correlated positively with the P-use efficiency (r² = 0.36); whereas the P-use efficiency correlated negatively with the P-uptake efficiency (r² = 0.50). Root surface did not determine P acquisition of pigeonpea, which absorbed 1.6 mg P cm^?3 from 33 cm³ soil compared with 0.17 mg P cm^?3 from 387 cm³ soil for cowpea at 66 d.     

Influence of Soil Properties and Manure Sources on Phosphorus in Runoff during Simulated Rainfall

Runoff from agricultural fields amended with animal manure or fertilizer is a source of phosphorus (P) pollution to surface waters, which can have harmful effects such as eutrophication. The objectives of this study were to evaluate the impact of soil P status and the P composition of manure sources on P in runoff and characterize the effects of manure sources on mass loss of dissolved reactive P, total dissolved P, and total P in runoff. Soil boxes set at 5% slopes received 7.5 cm h^?1 of simulated rainfall for 30 min. Study soils included a Kenansville loamy sand (loamy siliceous subactive thermic Arenic Hapludults, a Coastal Plain soil) and a Davidson silt loam (kaolinitic thermic Rhodic Kandiudults, a Piedmont soil). Soil test P concentrations ranged from 16 to 283 mg P kg^?1. Sources of P included broiler litter, breeder manure, and breeder manure treated with three rates of aluminum sulfate (Al₂(SO₄)₃) 0, 3.9, and 7.8 kg m^?2, di-ammonium phosphate (DAP), and an un-amended control. All manure sources were surface applied at 66 kg P ha^?1 without incorporation. Water extractable P represented an average of 10 ± 6% total P in manure. Runoff samples were taken over a 30-min period. Piedmont soil contained greater amounts of clay, aluminum (Al), and iron (Fe) concentrations, and higher P sorption capacities that produced significantly lower dissolved reactive P, total dissolved P, and total P losses than the Coastal Plain soil. Runoff P loss did not differ significantly for low and high STP Coastal Plain soils. Water extractable P in manures accounted for all dissolved reactive P lost in runoff with dissolved reactive P correlating strongly with water extractable P concentration (r² = 0.9961). Overall, manures containing the highest water extractable P concentrations contributed to the largest amounts of dissolved reactive P in runoff. Manure treated with 3.9 and 7.8 kg m^?2 of Al₂(SO₄)₃ (alum) decreased dissolved reactive P in runoff by 29%. While this soil box runoff study represents a worst-case scenario for P loss, highly significant effects of soil properties and manure sources were obtained. Management based on these results should help ameliorate harmful effects of P in runoff.     

Phosphorus Nutrition of Lowland Rice in Tropical Lowland Soil

Rice is a main food crop for about half of the world's population, and phosphorus (P) is the main limiting nutrient in rice production in tropical lowlands. A greenhouse experiment was conducted to evaluate P requirements of lowland rice grown on a lowland soil (Inceptisol). Dry matter, grain yield, and yield-attributing characteristics were significantly (P < 0.01) influenced by P fertilization. Based on quadratic response, maximum shoot dry weight and grain yield were obtained with the application of 190 mg P kg^?1 of soil. Maximum panicle, tiller number, and plant height were obtained with the application of 177 192, and 175 mg P kg^?1 of soil, respectively. Mehlich 1–extractable P for maximum grain yield was 15.6 mg kg^?1 of soil. Variability in grain yield with plant growth and yield parameters was in the order of tiller > shoot dry weight > panicle number > spikelet sterility > plant height > grain harvest index > panicle length > weight of 1000 grains. Phosphorus uptake in shoot and concentration and uptake in grain significantly (P < 0.01) increased grain yield. However, variability in grain yield was greater with concentration and uptake of P in the grain. Similarly, P harvest index was also significantly associated with grain yield. Agronomic P-use efficiency, apparent P-recovery efficiency, and P-utilization efficiency decreased quadratically with increasing P rates, whereas physiological P-use efficiency increased quadratically and agrophysiological P-use efficiency decreased linearly with increasing P rates. Agrophysiological and utilization P-use efficiencies had significant positive correlation with grain yield.     

Nitrogen Mineralization of Two Manures as Influenced by Contrasting Application Methods under Laboratory Conditions

The decomposition and the associated nitrogen (N) dynamics of organic N sources are affected by their contact with soil. While several authors have examined the effect of surface application or incorporation of crop residues on their decomposition rate, less information is available about the relationship between the placement of animal manure and their N mineralization rate. This study investigated the influence of chicken manure and cattle manure placement on soil N mineralization. The manures were incorporated or surface applied at 175 mg N kg^?1, and N release was periodically determined over 56 days by measuring inorganic N [nitrate (NO₃ ^?) N and ammonium (NH₄ ⁺) N] in a 2 M potassium chloride (KCl) extract at a ratio of 1:10 (w/v). Results indicated that the control soil released a maximum of 64 mg N kg^?1 soil at day 21, a sixfold increase over the initial concentration, which indicates its substantial mineralization potential. Manure treatments showed an initial increase in net NO₃ ^?-N content at the start of the experiments (until day 7) before an extended period of immobilization, which ended at day 21 of the incubation. A small but positive net N mineralization of all manures was observed from 28 days of incubation. At each sampling time, the mean mineral N released from the control was significantly less (P < 0.01) than surface-applied chicken manure, incorporated chicken manure, and surface-applied cattle manure. Treatments exceptions were at days 21 and 28 where N immobilization was at its peak. In contrast, incorporation of cattle manure showed a different N-release pattern, whereby the mineral N amount was only significantly greater than the control soil at days 42 and 56 with 84 and 108 mg N kg^?1 soil respectively. Incorporation of chicken manure and cattle manure did not favor nitrification as much as surface application and cattle manure caused a much greater immobilization when incorporated than when surface applied.     

Effect of organic,inorganic, and combined organic and inorganic P fertilization on plant P uptake and soil P pools

Phosphorus (P) is a limited resource, and its efficient use is a main task in sustainable agriculture. In a 6‐year field experiment on a loamy‐sand soil poor in P, the effects of organic, inorganic, and combined organic‐inorganic fertilization on crop yield, P uptake into grain, and soil properties (organic matter [OM] content, pH, water‐extractable P [P_w], double lactate–extractable P [P_dl], oxalate‐extractable P [P_ox], P‐sorption capacity [PSC], and degree of P saturation [DPS]) were investigated for the maritime climate in northeast Germany. Nine treatments were compared: a control treatment without fertilizer application, two organic fertilizers (cattle manure [CM] and biowaste compost [BC]; applied at a rate of 30 t ha^–1 in autumn 1998 and 2001), application of triple‐superphosphate (TSP; applied once a year either in autumn or in spring to evaluate the effects of application date), and combinations of organic and inorganic fertilizations. Several winter and spring crops (oilseed rape, barley, wheat) were cultivated according to good agricultural practice. The 6 year–average yield and P uptake were significantly higher for fertilized plots than for nonfertilized plots. Although the combination of organic × inorganic fertilizers resulted in higher soil P contents, significant yield increases were only found when organic fertilization was combined with TSP in spring. Small effects of P supply on yield in some years indicate that plant‐available soil P (despite of low P_dl values) was sufficient for crop growth. Phosphorus supply affected soil P_dl and P_w more than the parameters measured in the oxalate extract (P_ox, PSC, DPS). In general, periodically applied cattle manure and biowaste compost had the same effect on yield, P uptake, and soil P status as annually applied soluble mineral P.     

Long-term amendment of four different compost types on a loamy silt Cambisol: impact on soil organic matter,nutrients and yields

This study investigated the long-term effects of different composts (urban organic waste compost (OWC), green waste compost (GWC), cattle manure compost (MC) and sewage sludge compost (SSC)) compared to mineral fertilisation on a loamy silt Cambisol, after a 7-year start-up period. The compost application rate was 175 kg N ha^?1, with 80 kg mineral N ha^?1 and without. Soil characteristics (soil organic carbon (SOC), carbon-to-nitrogen (C/N) ratio and soil pH), nutrients (nitrogen (N), phosphorous (P) and potassium (K)) and crop yields were investigated between 1998 and 2012. SOC concentrations were increased by compost applications, being highest in the SSC treatments, as for soil pH. N contents were significantly higher with compost amendments compared to mineral fertilisation. The highest calcium-acetate-lactate (CAL)-extractable P concentrations were measured in the SSC treatments, and the highest CAL-extractable K concentrations in the MC treatments. Yields after compost amendment for winter barley and spring wheat were similar to 40 kg mineral N ha^?1 alone, whereas maize had comparable yields to 80 kg mineral N ha^?1 alone. We conclude that compost amendment improves soil quality, but that the overall carbon (C) and N cycling merits more detailed investigation.     

Sediment and phosphorus transfer in overland flow from a maize field receiving manure

Abstract. The transfer of suspended sediment (SS) and phosphorus (P) in overland flow from 30 m² field plots receiving either nil, surface‐applied or incorporated manure (slurry) were monitored to determine the vulnerability of land cropped to continuous forage maize to diffuse pollutant transfer in winter runoff. In the absence of slurry, P export was dominated by particulate forms, with up to 1 t SS ha^?1 and 0.75 kg total P ha^?1 collected from an individual storm event. Background concentrations of P in soluble (<0.45 μm) form were large (c. 0.5 mg L^?1) by eutrophication standards due to the previous build‐up of soil P, and largely independent of SS concentrations. Largest P exports (representing up to 23% of the slurry P applied) were measured when dairy slurry (3–13% dry solids) was surface‐applied. The P mobilized from the slurry accounted for up to 60% of total plot P export, with the majority occurring in a soluble bioavailable form during the first storm event. Initial P concentrations in runoff were in proportion to the amount of slurry P applied and significantly lower where rainfall was delayed after application. In one year, splitting the slurry application (3 × 10 kg ha^?1) reduced total P export by 25% compared to a single surface application (30 kg P ha^?1). In two years, incorporation of slurry, either by ploughing, or by tine cultivation, reduced the amount of overland flow by 50%, and the amount of P export by up to 60%, compared to the surface‐applied slurry treatments. Timeliness of slurry spreading to avoid periods of wet weather and simple cultivation of maize fields after harvest are practical and effective options to minimize SS and P transfer in land runoff from maize fields. The results also draw attention to the need to grow maize, and apply slurry to fields with a low P loss risk.     

Changes in Soil pH and Extractable Phosphorus Following Application of Turkey Manure Incinerator Ash and Triple Superphosphate

During the incineration of turkey manure, a wide variety and concentration of nutrients are conserved in the turkey manure ash (TMA). In particular, the high concentration of citrate-soluble phosphorus (P) (43 g kg^?1) may make it a suitable P source for crop production. The ash is alkaline with a pH of 12.2. We conducted a soil incubation study using a low-P soil with a pH of 6.2 to evaluate the effects of TMA on soil pH and extractable P. Two TMA rates, based on citrate-soluble P (10.9 and 21.9 mg kg^?1), were compared with equivalent rates of triple superphosphate (TSP). In addition, a 0-P control was included. At the rates tested, TMA slightly increased soil pH, but this increase would be of minor agronomic importance. At equivalent P rates, changes in water-soluble P (WSP) concentrations with TMA and TSP were similar. Changes in iron-oxide-strip–extractable P (FeO P) and Bray 1 P concentrations were greater with TMA than with TSP. In contrast, changes in Olsen P concentrations were greater with TSP than with TMA for up to 32 days. For TMA, the ability of the tests to extract P was ranked, from highest to lowest, as Bray 1 P > FeO P > Olsen P > WSP, and for TSP they were ranked Bray 1 P ≥ Olsen P ≥ FeO P > WSP. However, the Bray 1 P and FeO P tests tended to overestimate plant-available P because they measured more citrate-soluble P than that added with TMA. We conclude that TMA can be used as a P source for crop production and that the Olsen test may provide a better estimate of plant-available P in TMA-amended soil.     

Soil and nutrients losses under different crop covers in vertisols of Central India

Purpose

Accelerated erosion removes fertile top soil along with nutrients through runoff and sediments, eventually affecting crop productivity and land degradation. However, scanty information is available on soil and nutrient losses under different crop covers in a vertisol of Central India. Thus, a field experiment was conducted for 4 years (2010–2013) to study the effect of different crop cover combinations on soil and nutrient losses through runoff in a vertisol.

Materials and methods

Very limited information is available on runoff, soil, and nutrient losses under different vegetative covers in a rainfed vertisol. Thus, the hypothesis of the study was to evaluate if different crop cover combinations would have greater impact on reducing soil and nutrient losses compared to control plots in a vertisol.

This experiment consisted of seven treatment combinations of crop covers namely soybean (Glycine max) (CC₁), maize (Zea mays) (CC₂), pigeon pea (Cajanus cajan) (CC₃), soybean (Glycine max)?+?maize (Zea mays) ??1:1 (CC₄), soybean (Glycine ma x))?+?pigeon pea (Cajanus cajan) ?2:1 (CC₅), maize (Zea mays)?+?pigeon pea (Cajanus cajan) ??1:1 (CC₆), and cultivated fallow (CC₇). The plot size was 10?×?5 m with 1% slope, and runoff and soil loss were measured using multi-slot devisor. All treatments were arranged in a randomized block design with three replications.

Results and discussion

Results demonstrated that the runoff and soil loss were significantly (p?<?0.05) higher (289 mm and 3.92 Mg ha^?1) under cultivated fallow than those in cropped plots. Among various crop covers, sole pigeon pea (CC₃) recorded significantly higher runoff and soil loss (257 mm and 3.16 Mg ha^?1) followed by that under sole maize (CC₂) (235 mm and 2.85 Mg ha^?1) and the intercrops were in the order of maize?+?pigeon pea (211 mm and 2.47 Mg ha^?1) followed by soybean?+?maize (202 mm and 2.38 Mg ha^?1), and soybean?+?pigeon pea (195 mm and 2.15 Mg ha^?1). The lowest runoff and soil loss were recorded under soybean sole crop (194 mm and 2.27 Mg ha^?1). The data on nutrient losses indicated that the highest losses of soil organic carbon (SOC) (25.83 kg ha^?1), total nitrogen (N), phosphorus (P), and potassium (K) (7.76, 0.96, 32.5 kg ha^?1) were recorded in cultivated fallow (CC₇) as compared to those from sole and intercrop treatments. However, sole soybean and its intercrops recorded the minimum losses of SOC and total N, P, and K, whereas the maximum losses of nutrients were recorded under pigeon pea (CC₃). The system productivity in terms of soybean grain equivalent yield (SGEY) was higher (p?<?0.05) from maize?+?pigeon pea (3358 kg ha^?1) followed by that for soybean?+?pigeon pea (2191 kg ha^?1) as compared to sole soybean. Therefore, maize?+?pigeon pea (1:1) intercropping is the promising option in reducing runoff, soil-nutrient losses, and enhancing crop productivity in the hot sub-humid eco-region.

Conclusions

Study results highlight the need for maintenance of suitable vegetative cover as of great significance to diffusing the erosive energy of heavy rains and also safe guarding the soil resource from degradation by water erosion in vertisols.

     

EFFECT OF DIFFERENT PHOSPHORUS SOURCES ON THE GROWTH,YIELD, ENERGY CONTENT AND PHOSPHORUS UTILIZATION EFFICIENCY IN MAIZE AT RAWALAKOT AZAD JAMMU AND KASHMIR,PAKISTAN

Effect of poultry manure (PM) and four inorganic phosphorus (P) fertilizers sources, i.e., diammonium phosphate (DAP), single super phosphate (SSP), nitrophos (NP) and triple super phosphate (TSP) on crop production and P utilization efficiency (PUE) of maize was studied. Both inorganic P fertilizers and PM applied alone or combined in 50:50 proportions at equivalent rate of 90 kg P₂O₅ ha^?1. Results indicated that inorganic P sources with PM significantly increased plant height, leaf area and chlorophyll content. Average values showed that combined application of inorganic P with PM increased grain yield by 19 and 41% over inorganic P and PM alone, respectively. Similarly, increase in P-uptake due to the combined application of inorganic P + PM was 17% compared to sole inorganic P. Phosphorus utilization efficiency of inorganic P was increased with PM and the highest PUE was recorded in DAP + PM. Generally, combination of DAP + PM proved superior over the remaining P fertilizers.     

The effect of organic and chemical fertilizers on oilseed rape productivity and weed competition in short rotation

Abstract

A two-year field experiment was conducted to investigate the impact of short crop rotation and organic amendments on rapeseed yield under weed competition conditions. The primary experimental plots consisted of either triticale or pea as a prior crop, consisting of four subplots with either 25 tons of composted cattle manure (CCM), 150?kg urea N ha^?1 (N), 25 tons composted cattle manure + 75?kg urea N ha^?1 (CCM?+?N), or no urea N or manure added as the control (C0). Rapeseed seed yield was not significantly affected by previous crops, except for rapeseed grown after pea which had slightly higher seed yield (2058?kg ha^?1) than those grown after triticale (1942?kg ha^?1). Plants that received CCM?+?N produced the highest amount of seed yield (2447?kg ha^?1), but were not significantly different from plants that received just urea N (2218?kg ha^?1). Weeds gained more biomass when the previous crop was pea compared to those whose previous crop was triticale. Weeds in plots that received CCM?+?N produced the greatest biomass, followed by N, and CCM plots, respectively.