Increasing Application Rates Research Articles

有机肥替代部分化肥对长期连作棉田产量、土壤微生物 数量及酶活性的影响

施用有机物是作物增产、增加土壤有机质和改善土壤生物学性状的有效措施.在大田滴灌条件下,采用土壤酶学和微生物平板培养方法,研究了常规施肥(CF)减量20%-40%,配施3000、6000 kg/hm²有机类肥料对棉花产量、土壤微生物数量及土壤酶活性的影响.结果表明:降低CF用量20%-40%情况下,滴灌棉田配施3000、6000 kg/hm²的有机类肥料可获得与CF处理相持平的产量(4945-4978 kg/hm²),有机肥和生物有机肥配施处理间的棉花产量差异不显著(<em>P</em> < 0.05).细菌、放线菌和假单胞杆菌数量均随有机肥用量的增加而升高,不同类有机肥配施间表现为OF+BF > BF > OF;真菌数量则随有机肥施量升高而降低,其中OF+BF配施处理最为显著.有机无机肥配施显著提高了土壤酶活性,80% CF和60% CF与有机肥配施处理土壤碱性磷酸酶、荧光素二乙酸酯酶(FDA)、β-葡萄糖苷酶和脱氢酶的活性比CF处理分别升高了3.8%、17%、18%、55%和10.1%、19%、20%、60%,不同类型有机肥对土壤酶活性影响差异不显著.土壤细菌/真菌比、土壤放线菌/真菌和假单胞杆菌/真菌比均随有机肥施量的增加而升高,施用化肥或有机肥均显著降低了假单胞杆菌/细菌比.细菌、放线菌和假单胞杆菌数量与土壤脱氢酶、β-葡萄糖苷酶、碱性磷酸酯酶和荧光素二乙酸酯酶活性均呈显著或极显著正相关,真菌数量与4种酶活性呈负相关.CF减量20%-40%配施以3000、6000 kg/hm²有机肥不仅不会导致棉花减产,而且对提高土壤酶活性、调节土壤细菌、真菌、放线菌群落组成结构,改善北疆绿洲滴灌棉田土壤生物学性状有显著作用.;Organic fertilizer application is an effective approach to enhancing soil organic matter, soil biological activity as well as crop yield in agriculture. In the present research, a two-year field experiment was established to study the impacts of combined use of organic fertilizer with chemical fertilizer (CF) on cotton yield, soil microbial biomass, soil enzyme activities and soil microbial community structural composition in drip-irrigation condition in northern Xinjiang. Compared with CK, 100% chemical fertilizer treatment (300 kg N/hm², 90 kg P₂O₅/hm², 60 kg K₂O/hm²) or treatments of organic manure at different rates combined with chemical fertilizer significantly increased (<em>P</em> < 0.05) cotton yield. With chemical fertilizer or organic manure supply, cotton yield could be reached up to 4945-4978 kg/hm², however, there was no statistical difference (<em>P</em> < 0.05) among 100% CF fertilization and treatments with 20% to 40% chemical fertilizer substituted by 3000-6000 kg/hm²organic fertilizer. The number of soil bacteria, actinomycetes as well as pseudomonas significantly increased with increasing amendment rate of organic manure, but the number of soil fungi decreased with organic fertilizer rates increasing. For instance, the number of soil bacteria increased by 13%-41% in the treatments of organic manure at different rates combined with CF than in the treatment with 100% CF, whereas, the number of soil fungi in the treatment with 100% CF fertilizer is 1.4-1.6 times higher than that in the treatment with organic manure combined with CF at budding stage of cotton. Organic fertilizer application significantly enhanced (<em>P</em> < 0.05) soil enzyme activities. Compared with the treatment with 100% CF supply, soil enzyme activities of alkaline phosphatase, fluorescein acetate esterase, β-glucosidase and dehydrogenase increased by 3.8%, 17%, 18% and 55% in the treatments with 80% CF combined with 3000 kg/hm² organic manure, and increased by 10.1%, 19%, 20%, and 60% in the treatments with 60% CF fertilizer combined with 6000 kg/hm² organic manure (BF-organic), respectively. The ratios of soil bacteria/fungi, soil actinomycetes/fungi and pseudomonas/fungi increased with increasing application rate of organic manure, but pseudomonas/bacteria ratio markedly reduced in the treatment with 100 CF or organic fertilizer supply. A significant positive correlation (<em>P</em> < 0.05) was observed between the number of soil bacteria, actinomycetes and pseudomonas was significantly positively correlated with the activity of soil enzymes including dehydrogenase, β-glucosidase, alkaline phosphatase and fluorescein acetate esterase, respectively. However, an obvious negative correlation was observed between soil fungi number and the activity of soil enzymes such as dehydrogenase, β-glucosidase, alkaline phosphatase and fluorescein acetate esterase. Our conclusion is that 20%-40% of total chemical fertilizer application rate can be substituted by 3000-6000 kg/hm² organic fertilizer with no cotton yield decrease. Moreover, organic fertilizer addition addition plays a significant role in increasing soil enzyme activities, regulating soil microbial community structural composition as well as improving soil biological properties in cotton mono-cropping system under drip-irrigation condition in northern Xinjiang.

Potassium Fertilization and Physiological Soybean Seed Quality

The purpose of this study was to evaluate the influence of increased application rates of potassium on the physiological quality of seeds from different soybean cultivars. Seeds from two locations (Sao Gotardo, MG and Lavras, MG, Brazil) were used. After harvest, the seeds were sent to the Cen- tral Seed Analysis Laboratory of the Federal University of Lavras. We used a randomized design in a 4 × 6 factorial arrangement of four cultivars and six doses of potassium. All tests were performed with two replicates of 50 seeds (300 seeds per treatment). Germination, emergence under con- trolled conditions, accelerated aging, electrical conductivity, and tetrazolium tests were per- formed. Data were subjected to analysis of variance. In soybean seed production fields with high potassium content in the soil, higher application rates of potassium do not increase the physiolog- ical quality of seeds.

Large differences in soil phosphorus solubility after the application of compost and biosolids at high rates

Phosphorus (P) solubility was studied in a sandy loam after the application of high and increasing application rates (40, 80 and 120 tonnes DM ha−1) of two composts and two biosolids (treated sewage sludge). In 7.5-L pots, the products were mixed into the soil (pH 6.2) and perennial ryegrass was sown. After two years, the soil was analysed for PAL, water-extractable P (Pw), pH and oxalate-extractable Al and Fe. In compost- and biosolids-amended soils, PAL ranged from 72 to 126% and Pw from 53 to 169% of those measured in the unamended control. Due to high application rates, the products also had indirect effects on P solubility by elevating the pH or changing the P sorption capacity of the soil. The P sorption capacity of acidic soils was highly correlated to PAL (r2=0.75) and Pw of the soil (r2=0.70). Despite high PAL concentrations in the original soil (150 mg kg−1 DM), the highest application rates of the biosolids with high Al and Fe content were found to inhibit P supply to plants in the first months after application.

English

&nbsp; We used a stochastic production frontier and a Tobit model to evaluate technical efficiency and inefficiency of Bulgarian limited resource peanut farms for the period 2000/2002. We used a Just-Pope model to examine risks related to on-farm yield adjustments. Technical efficiency of farms ranged from 77 to 97%, with an average 92%, a median of 93%, mode of 90%, and skewness -1.49. The technical efficiency of these farms are largely influenced by on-farm decisions, the quantity of seeds, phosphate, fungicide, the amount investment capital, hours of manual labor used, and leased mechanized labor. The results indicate that efficiency is more crop specific than farm size dependent. Farm inefficiency was unrelated to size but rather to gender and age of operator. Farmers used less than the optimum levels of seeds and phosphate but there was risk associated with an increase in application rates of these inputs. These findings indicate that limited resource Bulgarian peanut farms are approaching efficiency, and adjustment to attain greater efficiency may be influenced by socio-demographic factors and limited government intervention. &nbsp; Key words:&nbsp;Production, efficiency, peanuts, Bulgaria.

Rice dry matter and nitrogen accumulation, soil mineral N around root and N leaching, with increasing application rates of fertilizer

Rice morphology and N leaching, together with mineral N in the soil and soil solution around root, were determined at different growth stages in a 3-year experiment located in the Taihu Lake region, China. The results showed that the N application rates had little impact on the soil mineral N around root, but increased the dry matter and N accumulation aboveground in the high fertility soil (55.3mgkg−1 of soil mineral N before rice season in 2008). However, no significant difference in grain yield was observed in all N treatments in these 3 years. Path analysis showed that spikelet per panicle made the greatest direct contribution (0.781) and total contribution (0.309) to grain yield compared to other yield components. And a higher panicle per m2 and dry matter accumulation resulted in yield decline later in the season due to a decline in the percentage of filled grains.No significant increases in plant N uptake, regardless of N application rates, were observed at the seedling stage, which indicated that lower N application rates could suffice during the rice early growing stages. Nitrate contents, in spite of high N rates input, in the percolation water were all below 1.0mgL−1 throughout the rice growing season. The increased N rates showed an increment of total N leaching through the percolation water, but not significant. The cumulative total N leaching only accounted for 1.86–4.96% of N fertilizer input, which suggested the N leaching should not be considered as main pollution resources in paddy filed in summer rice season. However, the evaluation of N leaching in different stages indicated that N leaching at seedling stage was larger in dominant (averaged 39.8% of total N leaching) than other stages. For the lower absorbing ability of rice seedling and more N leaching risk, suggestions on N fertilizer reduction should be made at rice early growing stage in this region.

Effect of Clean Coal Combustion Products in Reducing Soluble Phosphorus in Soil I. Adsorption Study

The study examined the effectiveness of various coal combustion products (CCPs) [fly ash (FA), fluidized bed combustion ash (FBC), and flue gas desulfurization gypsum (FGD)] on phosphorus (P) adsorption in soils using batch sorption studies. The results indicated that P adsorption increased with increasing application rates of CCPs. The effect of CCPs in increasing P adsorption followed: FBC > FA > FGD. There was an inverse relationship between the CCP-induced increase in P adsorption and initial soil pH, demonstrating that acidic and neutral soils responded more effectively to CCP addition than alkaline soils. The increases in soil pH and calcium (Ca) concentration in the soil solution resulting from CCP application enhanced P retention through adsorption and precipitation reactions.

Effect of Feeding Selenium-Fertilized Alfalfa Hay on Performance of Weaned Beef Calves

Selenium (Se) is an essential micronutrient in cattle, and Se-deficiency can affect morbidity and mortality. Calves may have greater Se requirements during periods of stress, such as during the transitional period between weaning and movement to a feedlot. Previously, we showed that feeding Se-fertilized forage increases whole-blood (WB) Se concentrations in mature beef cows. Our current objective was to test whether feeding Se-fertilized forage increases WB-Se concentrations and performance in weaned beef calves. Recently weaned beef calves (n = 60) were blocked by body weight, randomly assigned to 4 groups, and fed an alfalfa hay based diet for 7 wk, which was harvested from fields fertilized with sodium-selenate at a rate of 0, 22.5, 45.0, or 89.9 g Se/ha. Blood samples were collected weekly and analyzed for WB-Se concentrations. Body weight and health status of calves were monitored during the 7-wk feeding trial. Increasing application rates of Se fertilizer resulted in increased alfalfa hay Se content for that cutting of alfalfa (0.07, 0.95, 1.55, 3.26 mg Se/kg dry matter for Se application rates of 0, 22.5, 45.0, or 89.9 g Se/ha, respectively). Feeding Se-fertilized alfalfa hay during the 7-wk preconditioning period increased WB-Se concentrations (P Linear<0.001) and body weights (P Linear = 0.002) depending upon the Se-application rate. Based upon our results we suggest that soil-Se fertilization is a potential management tool to improve Se-status and performance in weaned calves in areas with low soil-Se concentrations.

유기성 폐기물 장기시용 후 토양에서 무 (Raphanus sativus cv. sodamaltari)의 중금속 흡수

This study was carried out to understand the long-term effects of organic waste treatments on the fate of heavy metals in soils originated from the organic wastes and consequent uptake of heavy metals by plant, together with examination of changes in soil properties and plant growth performance. In this study, the soils treated with three different organic wastes (municipal sewage sludge, alcohol fermentation processing sludge, pig manure compost) at three different rates (12.5, 25.0, 50.0 ton <TEX>$ha^{-1}yr^{-1}$</TEX>) for 7 years (1994 - 2000) were used. To see the long-term effect, plant growth study and soil examination were conducted twice in 2000 and 2010, respectively. There was no additional treatments of organic wastes for 10 years after the organic waste treatment for 7 years. Compared to plant growth examination conducted in 2000 using radish (Raphanus sativus cv. sodamaltari), it appeared that height, root length and diameter, fresh weight of radish grown in 2010 decreased in the plots treated with municipal sewage sludge and alcohol fermentation processing sludge and that the extent of decrease was higher with increase of sludge application rates. On the other hand, pig compost treatment increased plant height, root length and diameter, fresh weight with increasing application rates. Cu and Pb concentrations in radish root and leaves increased in 2010 compared to those in 2000 while Ni concentrations in root and leaves decreased. Zn concentration was increased only in the soils treated with pig manure compost. Multiple regression analysis among heavy metal species fractions in soils, soil pH, and metal concentrations in radish root and leaves indicated that the metal uptake by radish was governed mainly by the soil pH and subsequent increase of available heavy metal fractions in soils with organic waste treatments.

Fractions of Cu, Cd, and enzyme activities in a contaminated soil as affected by applications of micro- and nanohydroxyapatite

With the rapid development of nanotechnology, hydroxyapatite-based nanoparticles have been applied in wastewater and soil remediation. However, limited studies have been conducted on the remediation of heavy metal-contaminated soils by microhydroxyapatite (MHA) and nanohydroxyapatite (NHA). Thus, we investigated the effects of MHA and NHA on soil pH values and fractions of copper (Cu) and cadmium (Cd). The changes of soil enzymes with application of MHA and NHA were also evaluated. Pots contained 200 g of the soil with MHA and NHA ranging from 1 % to 5 % incubated for 60 days under greenhouse condition, and maintained at 60 % of soil water holding capacity by adding deionized water. Soil pH, catalase, urease, and acid phosphatase were analyzed at incubation times of 7, 14, 30, and 60 days by chemical assays. The fractions of Cu and Cd were analyzed after 60 days by a sequential extraction procedure. Application of MHA and NHA significantly increased soil pH values. Especially, we found for the first time that soil pH values with 3 % (pH > 7.90) and 5 % (pH > 8.83) application rates of MHA were larger than that of MHA itself (pH = 7.71). MHA was more effective than NHA in immobilizing Cu and Cd by significantly decreasing exchangeable fractions of Cu and Cd and transforming them from active to inactive fractions. Soil catalase and urease significantly increased, but acid phosphatase apparently decreased with increasing application rates of MHA. However, three enzymes activities changed slightly for NHA treatments. MHA was more effective than NHA in immobilizing Cu and Cd. MHA had a more positive effect on soil catalase and urease activities than NHA. Furthermore, Pearson’s correlation coefficients showed that soil pH value was a key factor to influence the bioavailability of Cu and Cd and the activity of soil enzymes. The results of this study provided an efficient method for the remediation of heavy metal-contaminated soils.

Influence of compost amendments on the hydraulic functioning of brownfield soils

AbstractThis study assessed the impact of compost on the hydraulic properties of three soils (sandy loam, clay loam and diesel‐contaminated sandy loam) with relatively poor physical quality typical of brownfield sites. Soils were amended with two composts at 750 t/ha. Samples were also collected from a clay‐capped brownfield site, previously amended with 250, 500 or 750 t/ha of compost. Water‐release characteristics and saturated hydraulic conductivity were determined for all soils and physical quality indicators derived. Unsaturated flow in field profiles after compost application with two depths of incorporation and two indigenous subsoils was simulated using Hydrus‐1D. Compost generally increased water retention. Hydraulic conductivity tended to decrease following compost application in sandy loam but increased in clay and clay loam, where compost addition resulted in a larger dominant pore size. Although compost improved physical quality indicators, they remained suboptimum in clay and clay loam soil, which exhibited poor aeration, and in the contaminated sandy loam, where available water capacity was limited, possibly due to changes in wettability. Increasing application rates in the field enhanced water retention at low potentials and hydraulic conductivity near saturation but did not alter physical quality indicators. Numerical simulation indicated that the 500 t/ha application resulted in the best soil moisture regime. Increasing the depth of incorporation in the clay cap improved drainage and reduced waterlogging, but incorporation in more permeable subsoil resulted in prolonged dry conditions to greater depths.

Optimum application level of winter cover crop biomass as green manure under considering methane emission and rice productivity in paddy soil

The combined seeding and cropping of non-leguminous and leguminous cover crops during the cold fallow season is recommended as an important agronomic practice to improve total biomass productivity and soil fertility in mono-rice (Oryza sativa L.) cultivation system. However, application of plant residues as green manure can increase methane (CH4) emission during rice cultivation and affect rice quality and productivity, but its effects are not well examined. In this field study, the mixture of barley (Hordeum vulgare R.) and hairy vetch (Vicia villosa R., hereafter, vetch) seeds with 75 % recommended dose (RD 140 kg ha−1) and 25 % RD (90 kg ha−1), respectively, were seeded after rice harvesting in late November, 2010, and harvested before rice transplanting in early June 2011. Total aboveground biomass was 36 Mg ha−1 (fresh weight basis with 68 % moisture content), which was composed with 12 Mg ha−1 of barley and 24 Mg ha−1 of vetch. In order to determine the optimum recycling ratio of biomass application that can minimize CH4 emission without affecting rice productivity, different recycling ratios of 0, 25, 50, 75, and 100 % of the total harvested biomass were incorporated as green manure 1 week before rice transplanting in a typical temperate paddy soil. The same rates of chemical fertilizers (N–P2O5–K2O = 90–45–58 kg ha−1) were applied in all treatments. Daily mean CH4 emission rates and total CH4 fluxes were significantly (p < 0.05) increased with increasing application rates of cover crop biomass. Rice productivity also significantly (p < 0.05) increased with biomass application, but the highest grain yield (53 % increase over the control) was observed for 25 % recycling. However, grain quality significantly (p < 0.05) decreased with increasing cover crop application rates above 25 % recycling ratio, mainly due to extended vegetative growth periods of rice plants. Total CH4 flux per unit grain yield, an indicator used to simultaneously compare CH4 emission impact with rice production, was not statistically different between 25 % biomass recycling ratio and the control but significantly increased with increasing application rates. Conclusively, the biomass recycling ratio at 25 % of combined barley and vetch cover crops as green manure might be suitable to sustain rice productivity without increasing CH4 emission impact in mono-rice cultivation system.

Fertilization effects of organic waste resources and bottom wood ash: results from a pot experiment

We conducted a pot experiment to study the fertilization effects of four N- and P-rich organic waste resources alone and in combination with K-rich bottom wood ash at two application rates (150 kg N ha–1 + 120 kg K ha–1, 300 kg N ha-1 + 240 kg K ha–1). Plant-available N was the growth-limiting factor. 48–73% of N applied with meat and bone meal (MBM) and composted fish sludge (CFS) was taken up in aboveground biomass, resulting in mineral fertilizer equivalents (MFE%) of 53–81% for N uptake and 61–104% for yield. MFE% of MBM and CFS decreased for increasing application rates. Two industrial composts had weak N fertilization effects and are to be considered soil conditioners rather than fertilizers. Possible P and K fertilization effects of waste resources were masked by the soil’s ability to supply plant-available P and K, but effects on plant-available P and K contents in soil suggest that the waste resources may have positive effects under more nutrient-deficient conditions.

Comparative studies on soil nitrification inhibition by pyridine compounds

为了探明吡啶类化合物对土壤硝化作用的抑制效应, 采用室内微宇宙试验, 研究了 2-氯-6(三氯甲基)硫酸盐、2-氯-6(三氯甲基)盐酸盐、吡啶混合物和吡啶 X 类化合物对潮土、红壤和水稻土中铵态氮硝化的抑制作用。结果表明, 在 35 d 培养期内, 吡啶类化合物处理土壤硝态氮含量明显低于对照(未添加吡啶类化合物), 吡啶类化合物对土壤中铵态氮的硝化抑制率介于 2.91%~91.92%, 抑制强度先逐渐升高后降低, 在培养 21 d 时抑制强度达到峰值。不同类型吡啶类化合物对土壤中铵态氮的硝化抑制效果存在差异, 吡啶盐酸盐类化合物优于其他几类化合物; 吡啶类化合物对土壤中铵态氮的硝化抑制作用与土壤类型有关, 对 3 种土壤中铵态氮的硝化抑制作用表现为潮土>水稻土>红壤。就同一土壤而言, 硝化抑制强度随着吡啶类化合物用量的增加而增加。

Effects of combined thiamethoxam and diatomaceous earth on mortality and progeny production of four Pakistani populations of Rhyzopertha dominica (Coleoptera: Bostrichidae) on wheat, rice and maize

Bioassays were conducted to evaluate the effects of combining thiamethoxam at 0.25, 0.5 and 0.75 mg/kg of active ingredient with the diatomaceous earth (DE) formulation, SilicoSec, at the rate of 100 mg/kg against four Pakistan populations of the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). The tests were carried out with adult beetles on wheat, maize, and rice. Mortality increased with increasing application rates and exposure intervals for each population. Individually, thiamethoxam alone was more effective at the high dose rate than DE alone, but after 14 days of exposure in most cases, there was greater mortality with DE than with the low dose of thiamethoxam. There was greater mortality in wheat than in rice or maize. Populations differed in susceptibility to treatments and production of progeny.

Effects of natural and calcined poultry waste on Cd, Pb and As mobility in contaminated soil

The reuse of waste materials as soil additives could be a welcome development in soil remediation. The mobility of Cd, Pb and As in a contaminated soil was investigated using natural and calcined poultry wastes (eggshell and chicken bone), CaCO3 and CaO at different application rates (0, 1, 3 and 5 %). The chemical composition accompanied with mineralogical composition indicated that CaCO3 and CaO were the major components in natural and calcined eggshells, respectively, while hydroxyapatite (HAP) dominated the natural and calcined chicken bones. The results showed that soil pH tended to increase in response to increasing application rates of all soil additives. The effectiveness of the additives in reducing Cd, Pb and As mobility was assessed by means of chemical extractions with 0.1 N HCl for Cd and Pb or 1 N HCl for As, according to Korean Standard Test (KST) method. Both calcined eggshell and chicken bone were equally effective with CaO or CaCO3 in reducing the concentration of 0.1 N HCl-extractable Cd from 6.17 mg kg−1 to below warning level of 1.5 mg kg−1, especially at the highest application rate. The application of calcined eggshell, CaO and CaCO3 also decreased the concentration of 0.1 N HCl-extractable Pb from 1,012 mg kg−1 to below warning level of 100 mg kg−1. The Pb concentration decreased significantly with an increasing application rate of chicken bone, but remained above warning level even at the highest application rate. On the contrary, natural and calcined chicken bones led to a significant increase in the mobility of As when compared with the control soil. These findings illustrate that calcined eggshell in particular is equally effective as pure chemical additives in stabilizing Cd and Pb in a contaminated agricultural soil. The presence of As in metal-contaminated soils should be taken into consideration when applying phosphate-containing materials as soil additives, because phosphate can compete with arsenate on adsorption sites and result in As mobilization.

Earthworm Population Density in Sugarcane Cropping System Applied with Various Quality of Organic Matter

Earthworms population in the soil are greatly impacted by agricultural management, yet little is known about how the quality and quantity of organic matter addition interact in sugarcane cropping system to earthworm population. This study describes the effect of various organic matter and application rates on earthworms in sugarcane cropping system. Earthworms were collected in April, July and December from 48 experimental plots under five kinds of organic matter application : (1) cattle manure, (2) filter cake of sugar mill, (3) sugarcane trash, (4) mixture of cattle manure+filter cake, and (5) mixture of cattle manure+sugarcane trash. There were three application rates of the organic matter (5, 10, and 15 ton ha-1). The treatments were arranged in factorial block randomize design with three replications and one treatment as a control (no organic input). Earthworms were collected using monolith sampling methods and hand-sorted from each plot, and measured its density (D) (indiv.m-2), biomass (B) (g m-2) and B/D ratio (g/indiv.). All the plots receiving organic matter input had higher earthworm density, biomass, and B/D ratio than the control. The highest earthworm population density was found in the plot receiving application of sugarcane trash (78 indiv.m-2) and the mixture of cattle manure+sugarcane trash (84 indiv.m-2). The increase in application rates of organic matter could increase the earthworm density and biomass. Earthworm population density also appeared to be strongly influenced by the quality of organic matter, such as the C-organic, N, C/N ratio, lignin, polyphenols, and cellulose content. Earthworm preferred low quality organic matter. It was caused by the higher energy of low quality organic matter than high quality organic matter. Our findings suggest that the input of low quality organic matter with application rate as 10 ton ha-1 is important for maintaining earthworm population and soil health in sugarcane land.Keywords: earthworms, organic matter quantity, quality, sugarcane cropping system

Effect of fertilizer amount on yield and nutrient accumulation of green manures

大田试验条件下研究不同氮、磷、钾肥用量对绿肥[豆科绿肥紫云英(<i>Astragalus sinicus</i> L.)和禾本科绿肥看麦娘(<i>Alopecurus aequalis</i> Sobol.)]产量及养分积累量的影响。试验结果表明, 施肥能显著增加绿肥产量, 绿肥鲜草产量较不施肥处理增加42.8%~311.1%, 与缺素处理相比, 氮、磷、钾肥的增产率分别为57.1%~177.5%、27.8%~178.7%、14.2%~32.4%。两种绿肥的鲜草产量均随氮、磷、钾肥施用量的增加而增加, 中、高水平的氮、磷肥用量下看麦娘的产量均高于紫云英, 所有钾肥处理的看麦娘产量均高于紫云英。绿肥的养分积累量均随施肥量的增加而增加, 中高水平的氮、磷肥用量下看麦娘的氮、磷积累量高于紫云英, 不同钾水平下的看麦娘钾积累量均高于紫云英。氮、磷、钾肥用量分别为112.5 kg(N)·hm^-2、19.7 kg(P)·hm^-2、37.5 kg(K)·hm^-2时, 两种绿肥总产量及碳、氮、磷、钾积累量最高, 分别为49 424 kg·hm^-2和3 212 kg(C)·hm^-2、151 kg(N)·hm^-2、19.8 kg(P)·hm^-2、156 kg(K)·hm^-2。 此时看麦娘产量、碳、氮、磷、钾积累量分别占总量的59.0%、65.7%、66.3%和64.4%。紫云英田间自然洒种的看麦娘无成本投入且养分积累量高, 不失为一种优质绿肥。

Evaluation of Exponential Fertilization Technique for Cultivation of Turfgrass during Early Growth Period

The exponential fertilization method is based on the theory of supplying steady-state nutrition to young seedlings during the early, exponential growth stage. The objective of the research was to find the most effective method of fertilizing turfgrass during the early growth stage following seedling emergence. The field experiment was performed on turfgrass (tall fescue, Festuca arundinacea Schreb.) comparing a check (no fertilizer applied), two conventional fertilization techniques (equal additions and linearly increasing application rates over time) to the exponential additions fertilization method to test the relative effectiveness of this latter technique relative to conventional methods. Results show that the exponential growth period for fescue is the first 5 weeks following planting. Biomass accumulation, total nitrogen (N) concentration, and N content per seedling in turfgrass seedlings fertilized using the exponential addition fertilization technique were 32, 35, and 70% greater than those treated with traditional methods, respectively.

Cadmium distribution in rice plants grown in three different soils after application of pig manure with added cadmium

A glasshouse pot experiment was conducted to investigate Cd concentrations in the aboveground parts of two consecutive crops of rice and Cd availability in three different soils (loam, silt loam, and sandy loam) after application of pig manure with added Cd. Soil pH tended to increase with increasing application rate of pig manure from 1 to 3% (w/w, oven dry basis). Soil diethylene triamine pentaacetic acid (DTPA) extractable Cd showed a clear positive correlation with soil total Cd content and increased with increasing Cd amendment of the manure but showed no difference between the two manure application rates. Cd concentrations in the grain, husk, and straw were significantly and positively correlated with soil DTPA-extractable Cd (p < 0.001). Within each level of manure Cd, the higher rate (3%) of manure produced lower Cd concentrations in the grain, husk, and straw on all three soils than did the lower rate (1%) after the first crop, but this no longer occurred after the growth of the second crop. Grain Cd concentrations exceeded the Chinese National Food Quality Standard (0.2 mg kg(-1)) most often on the loam, with intermediate frequency on the silt loam, and least often on the sandy loam, the soil with the highest pH and lowest organic carbon content and cation exchange capacity.

Rehabilitation of a Sandy Soil With Aluminum-Water Treatment Residual

Water treatment residual (WTR) is a waste material from drinking water process. Land application is an option for aluminum-WTR (Al-WTR) disposal. A promising concept is application of Al-WTR and plant residue simultaneously for the rehabilitation of sandy soil quality. The objective of this study was to explore the changes in soil properties and growth of Bahia grass (Paspalum notatum F.) with application rates of Al-WTR ranging from 2.5% to 10% (wt/wt) and pine bark compost at a constant rate of 5.0% in a pot experiment. The results that indicate the soil bulk density, water-stable aggregates, and saturated hydraulic conductivity were improved by Al-WTR application. The Al-WTR application alone significantly (P < 0.05) decreased available P concentration in the soil, whereas the decrease in P availability could not be confirmed with the coapplication of Al-WTR. The coapplication of Al-WTR and compost increased microbial biomass carbon compared with application of Al-WTR alone in the soil. The rates of coapplication to the soil are safe with regard to heavy metals in the soil and plants. Shoot biomass production of grass increased significantly with increased application rate of Al-WTR.