Application Of Phosphate Fertilizers Research Articles

Protective effects of farnesol on a Rhizobium strain exposed to cadmium

Soil acts as a repository for many metals that human activity releases into the environment. Cadmium enters agricultural soils primarily from application of phosphate fertilizers and sewage sludge. Among soil bacteria, rhizobia have a great agronomic and environmental significance and are major contributors to a sustainable maintenance of soil fertility. However, the services that this group of microorganisms provides are affected by environmental constraints, such as Cd contamination. Bioactive compounds also influence soil microorganisms. Farnesol is a phytocompound with recognized bioactivity, inducing both beneficial and harmful effects. In this study, Rhizobium sp. strain E20-8 was exposed to sole or combined exposure to Cd and farnesol. Results showed that farnesol (25 and 200 µM) did not affect rhizobia; exposure to Cd (µM) inhibited rhizobia growth and induced several biomarkers of oxidative stress; exposure to the combination of farnesol and Cd reduced oxidative damage, and the highest concentration of farnesol tested reduced Cd accumulation and allowed a significant growth recovery. Farnesol protective effects on rhizobia exposed to Cd is novel information which can be used in the development of microbe-based environmental engineering strategies for restoration of metal contaminated areas.

Pertumbuhan dan Kandungan Minyak Atsiri Tanaman Selasih (Ocimum basilicum L.) pada Naungan dan Dosis Pupuk Fosfat yang Berbeda

ABSTRACT<br /><br />Basil (Ocimum basilicum L.) is a plant that has great potency to be developed. Almost all parts of the plant can be utilized. This study aimed to determine the effect of shade and phosphate fertilizer on growth and essential oil content in basil. This research was conducted at the experimental field of Agrotechnology Departement, Faculty of Agriculture, University of Trunojoyo Madura, during January-April 2015. The research was arranged in a split plot design with 3 replications. Main plot was shading i.e., without shading and 25% shading. The subplots were phosphate fertilizer rate, i.e., 0, 1.5, 3.0, and 4.5 g SP36 per plant that was planted in polybags. The results showed that plants treated with 25% of shading and applied with phosphate 3 g per plant had the highest total dry weight, production of essential oil and eugenol. Shading of 25% give the best results on plant height, leaf area and total fresh weight of the plant. Application of phosphate fertilizer 3 g per plant give the highest content of chlorophyll (chlorophyll b and total chlorophyll), while the highest essential oil and eugenol content of leaves is obtained from application of phosphate fertilizer 3 and 4.5 g per plant. Shading and phosphate fertilizer application did not affect leaf number. <br /><br />Keywords: chlorophyll, eugenol, leaf, phenylpropanoids, production<br /><br />

Економічна ефективність застосування рідких фосфорних добрив за вирощування картоплі столової на темно-сірому опідзоленому ґрунті

Економічна ефективність застосування рідких фосфорних добрив за вирощування картоплі столової на темно-сірому опідзоленому ґрунті

Influence of priming and nitrogen on growth behavior of buckwheat (Fagopyrum esculentum) in rainfed condition of midhill in Nepal

An experiment was conducted during winter, 2010/11 at IAAS, Lamjung with the objective of studying effect of seed priming and nitrogen levels on yield and yield attributing characters of buckwheat. Altogether, there were 9 treatments of seed priming hours (0, 18 and 36) combined with nitrogen levels (30, 45 and 60 kg/ha). The experiment was laid out in randomized complete block design and each treatment was replicated thrice. The seed priming of 36 hours had resulted in significantly higher germination percentage in both 15 days after sowing (DAS) (4.40%) and 30 (DAS) (5.74%) The total germination percentage was also significantly higher (48.4%) with 36 hr seed priming. The main and interaction effects of seed priming and nitrogen levels had significant influence on days to 50% flowering. The dry biomass per plant, grain yield, straw yield, harvest index and percentage moisture content of biomass at harvest were found non-significantly different due to seed priming and nitrogen levels. The highest value for dry matter accumulation per plant (5.24 gm/plant), straw yield (8706 kg/ha) and % moisture content (71.0%) was recorded with 36 hr seed priming whereas the highest value for grain yield (1599 kg/ha), and harvest index (19.8) was obtained with 18 hr seed priming. Likewise, dry matter accumulation (5.38 gm/plant), grain yield (1575 kg/ha) and harvest index (22.0) was found highest in 45 kg N/ha. Similarly, the straw yield (9153 kg/ha) and % moisture content (75.3%) was found highest in the treatment with 60 kg N/ha. The interaction effect between nitrogen level and priming was found non-significant and the highest grain yield (2091 kg/ha) was obtained from 18 hr seed priming with 45 kg N/ha. Phosphorus consumption rate was intrestingly higher in buckwheat plot with nitrogen application. Moderate consumption of potassium was also observed while nitrogen content in soil remain apparantly unchanged and similar was the case with soil pH and organic matter content. Application of phosphatic fertilizer would be benefitial for buckwheat cultivation. Further experiment should be done to verify the effective dose of fertilizer.Journal of the Institute of Agriculture and Animal Science. Vol. 33-34, 2015, Page: 47-54

Effects of phosphorus on absorption and transport of selenium in rice seedlings.

The effects of different concentrations of phosphorus (P) on absorption and transfer of selenium (Se) in rice seedlings were studied by hydroponics experiment. The interaction between iron plaque and phosphorus on absorption and transport of selenium were studied by adding a large amount of iron-induced iron plaque, to provide a theoretical basis for rational application of phosphate fertilizer in the selenium bio-strengthening process of rice. The results showed that phosphorus deficiency may result in the formation of reddish brown iron oxide coating on the root surface of rice. The formation of root iron plaque of rice is related to concentration of phosphorus, and low concentration of phosphorus (0-1.5mmolL-1) can increase the amount of root iron plaque. Compared P deficiency culture and 2mmolL-1 P culture, Se content in the shoots and roots decreased by 76 and 47%, respectively. Addition of Fe2+ significantly reduced biomass of shoot and had no significant effect on the roots; when the P concentration increased from 0.1 to 0.3mmolL-1, transfer coefficient of Se decreased. Therefore, both root iron plaques induced by phosphorus deficiency and iron addition have a strong adsorption effect on selenium, which reduces the transport of selenium from the rice roots to the shoots. In the lower range of phosphorus concentration, low phosphorus can promote selenium content of rice shoot, while higher on the contrary. In the practice of rice production, proper management of phosphorus nutrient is of great significance to control selenium content in rice grain.

Fluorine in soils under pasture following long-term application of phosphate fertiliser in New Zealand

An understanding of the rate at which fluorine (F) accumulates in soil from phosphorus fertiliser and how much is lost via leaching are important because of the challenge elevated F may pose to soil, plant and animal health. This study measured F accumulation in a soil under pasture (Inceptisol) that received single superphosphate (SSP) fertiliser over 63 years in a long-term fertiliser trial. It also assessed the downward movement of F in soil and effect of irrigation in a long-term irrigation trial. Results showed total F concentrations in topsoil (0–7.5 cm) that received 188 kg SSP ha−1 and 376 kg SSP ha−1 fertiliser increased from 251 mg kg−1 to 349 and 430 mg kg−1, respectively. The rates of F accumulation were estimated at 1.1 and 2.1 kg ha−1 yr−1 respectively, low compared to previous studies. The F concentration in the 376 kg SSP ha−1 treatment decreased with depth, but was significantly higher than the control treatment to 50 cm, suggesting movement of F down the soil. Fluorine concentrations also decreased with depth to 50 cm in soils that received either no irrigation or up to 770 mm yr−1 from irrigation. However there was no significant difference in the amount of F with depth between irrigation treatments. We postulate that F was moving predominately in drainage water in the period immediately after P fertiliser application in mid-winter and wasn't enhanced by irrigation. This study should be repeated for other soil types to help our understanding of the potential for ongoing F accumulation in soil and implications this may have on future land use.

Soil Physico-chemical Properties Changes under Different Crops in Ado Ekiti, Nigeria

The sustainable soil management necessary to maintain soil quality depends on the understanding of how the soil responds to agricultural practices over time. This paper reports the changes in physicochemical properties that resulted from different cropping systems on a soil in Ado Ekiti, Nigeria. Soil samples were collected from sole maize plot (1.0 ha), sole cowpea plot (1.0ha) and cassava/maize intercrop plot (0.6ha) on a land that was previously under fallow. The sand, silt and clay contents of the soil and some selected chemical parameters varied considerably within the study area (different cropping zones). The soil was generally sandy loam and was found to vary from slightly acidic to slightly alkaline and generally low in Soil Organic Matter (SOM) and Available P (Av. P) with no salinity problem. High magnitude of variability was observed for Electrical Conductivity (EC), Av. P and SOM while pH had the least magnitude. A geostatistical evaluation of the soil chemical properties showed moderate to strong spatial dependence. The geospatial maps clearly revealed the heterogeneity of the soil chemical properties across the field. Both classical statistics and geo-statistical analyses of the soil of the area provided a better understanding of the spatial variability of soil chemical properties and the influence that such could have on crop performance. The results indicated that the soil pH is slightly acidic and contained low amounts of both SOM and Av. P. It is suggested that planting of cover crops, minimum tillage and controlled application of phosphate fertilizer should be done so as to increase the SOM, improve Av. P and maintain the soil pH. Further studies should be conducted to include other soil chemical properties such that robust site specific management programme could be effected.

Comparative analysis of cadmium-induced stress responses by the aromatic and non-aromatic rice genotypes of West Bengal

Constant exposure of the living ecosystems to heavy metals, like cadmium (Cd), induces a detectable change at the biochemical and genetic level. Repeated application of phosphate fertilizers in paddy fields, leads to increase in Cd content of soil. Cd being highly mobile is transported to shoot and grain, thereby entering into the food chain of animal system. In the present study, treatment of 7-day old rice seedlings with 10μM cadmium chloride resulted in Cd toxicity across the seven non-aromatic and six aromatic rice cultivars and landraces used for the study. Free proline and malondialdehyde content of treated samples were higher in comparison to the untreated samples, which indicated Cd induced tissue damage in plants. Photosynthetic pigment content of treated samples was also found to be much lower in comparison to the untreated samples, which is probably due to peroxidation of membrane, leading to compromised and lower photosynthetic efficiency of treated plants. At the genetic level, Randomly Amplified Polymorphic DNA assay was found to efficiently detect the genetic polymorphisms (caused by alterations in DNA bases) induced by Cd. Production of unique polymorphic bands in Cd-treated plants helps in assessment of the degree of damage Cd imparts on the plant system. Cluster analysis was performed and the rice genotypes were grouped into five distinct clusters, with IR64 and Tulsibhog in two distinct groups. Based on the variability in responses, the 13 rice genotypes were grouped into sensitive and tolerant ones.

The importance of harvest residue and fertiliser on productivity of Pinus patula across various sites in their first, second and third rotations, at Usutu Swaziland

BackgroundConcern is growing about the future of forestry productivity due to intensive nutrient removal, as a result of different harvesting operations. This study aimed to determine the effects on forest productivity when using different slash-retention scenarios with the recommended amounts of mineral fertiliser in Usutu forest. Usutu is a plantation forest that grows mostly softwood where the predominant species is Pinus patula Schiede ex Schltdl. & Cham.MethodsThe first trial series (F) comprised of one trial located in each of five forest blocks. It was established in 1971 and compared the effects of various site preparation scenarios (slash removal, slash retention and cultivation) on the early growth of Pinus patula for adjacent first (F1R) and second rotation (F2R) sites (i.e. grassveld and clearfelled first-rotation sites). The second (S) trial series was re-established in April 1991 on exactly the same position as the first trial series, and involved second (S2R) and third rotation (S3R) sites. Three main treatments, standard pitting through harvest residue (control); manual pitting after removal of harvest residue and forest floor (cleared); and manual pitting and broadcast application of dolomitic lime (2 t ha− 1) over the slash (lime), were undertaken in factorial combination with the application of phosphate and potassium fertiliser. The data reported here are for tree volume productivity across the five sites of the first trial series up to age 10 years and three of the five sites of the second trial series up to age 9 years.ResultsSlash removal decreased volume productivity by 9 and 13% in the F1R and F2R at 10 years of age and further by 21 and 33% in S2R and S3R, respectively at 9 years of age. However, fertiliser application increased volume productivity by 14 and 15% in the F1R and F2R at 10 years age and further by 18 and 10% in the S2R and S3R, respectively at 9 years of age.ConclusionsIn order to sustain or increase productivity, it is recommended that harvest residue slash should be conserved and fertiliser containing phosphate and potassium be applied at planting at Usutu.

Rye cover crop increases earthworm populations and reduces losses of broadcast, fall-applied, fertilizers in surface runoff

Corn (Zea mays L.) silage and soybean [Glycine max (L.) Merr.] rotations in the US Upper Midwest leave minimal amounts of surface residues, which can contribute to soil degradation, increased surface runoff, and reduced water quality. Planting cover crops after harvest can reduce these concerns, but their effectiveness in reducing nutrient losses in surface runoff shortly after fall planting and fertilization has not been thoroughly investigated. Therefore, we applied 65 mm of simulated rainfall in 60 min to five replicate, 1.5 by 3.0 m, field plots in a no-till, corn silage-soybean rotation into which a rye (Secale cereale L.) cover crop was planted for 14 consecutive years and to five replicate plots with no cover crop history. Natural slope of the plots ranged from 0.1 to 2.7%. The study was conducted in October 2014, about one month after corn silage harvest and rye planting and ∼1 h after broadcast application of monoammonium phosphate and potassium chloride fertilizers. The living rye cover crop significantly (P ≤ 0.05) delayed surface runoff by 5.7 min and decreased total runoff by 65% compared to plots with no cover crop. This resulted in a significant 68% reduction in sediment loss and even greater significant reductions in fertilizer nutrient losses (i.e., NH4-N - 86%; total P - 83%; total dissolved P - 84%; K - 91%). Earthworm population and biomass, measured using electrical extraction shortly after the rainfall simulations, were 1.2 and 1.4 times greater in cover crop plots than in no cover plots and 3.2 and 2.5 times greater the following spring. Our results suggested that a living cover crop and their long-term usage can contribute to improvements in soil structure and increased earthworm populations that can substantially reduce sediment and nutrient losses in surface runoff due to a severe storm shortly after post-harvest broadcast application of fertilizer.

Effects of continuous fertilization on bioavailability and fractionation of cadmium in soil and its uptake by rice (Oryza sativa L.)

A four-year field trial was conducted in a rice paddy in southern China to determine the effects of continuous phosphate fertilizer, pig manure, chicken manure, and sewage sludge application on soil Cd accumulation in soil and Cd uptake by rice. The results showed that continuous application of fertilizers with higher Cd levels caused Cd to accumulate and redistribute in various soil fractions. In turn, these effects influenced Cd bioavailability in rice plants. After four years of phosphate fertilizer, pig manure, chicken manure, and sewage sludge application, the annual soil Cd accumulation rates were 0.007–0.032 mg kg−1, 0.005–0.022 mg kg−1, 0.002–0.013 mg kg−1, and 0.032–0.087 mg kg−1, respectively. Relative to the control, the pig- and chicken manure treatments significantly increased soil pH and reduced DTPA-extractable Cd (DTPA-Cd) and the exchangeable Cd fraction (Exc-Cd). In contrast, sewage sludge application significantly increased DTPA-Cd and Cd in all soil fractions. Phosphate fertilization had no significant effect on soil pH, DTPA-Cd, or Exc-Cd. Pearson's correlation coefficients showed that the rice grain Cd levels varied directly with DTPA-Cd, and Exc-Cd but inversely with soil pH. Pig- or chicken manure decreased rice grain Cd content, but sewage sludge increased both soil Cd availability and rice grain Cd uptake. Application of phosphate fertilizer had no significant effect on rice grain Cd content. The continuous use of organic- or phosphate fertilizer with elevated Cd content at high application rates may induce soil Cd accumulation and influence rice grain Cd accumulation.

Adubação fosfatada no feijoeiro cultivado sob palhada de Brachiaria brizantha cv. Marandu

ABSTRACT The application of phosphate fertilizer is indispensable for the achievement of sustainable bean production, and P is necessary practically in the entire cycle. Thus, cultural management alternatives have been used in the best use of this nutrient, among them the use of Brachiaria as cover crop. The objective of this research was to evaluate the dynamics of phosphorus in the soil with and without the presence of Brachiaria brizantha cv. Marandú as cover crop, and the bean response to phosphorus fertilization. We used a randomized block design with a split plot arrangement; the plots were composed of P2O5 doses (0, 50, 100, 200, and 400 kg ha-1) via triple superphosphate; and the subplots were composed of the presence and absence of Brachiaria as previous cover crop cultivation of beans. Soil samples were taken at 15 and 30 days after sowing (DAS) bean. In the samples, phosphorus fractionation in soil was carried out by the Hedley technique. Phosphorus content was evaluated in the leaf and grain yield of bean plants. The phosphorus fertilization and cultivation of Brachiaria brizantha cv. Marandú as cover crop provided changes in the levels of labile P of soil at 15 and 30 DAS bean, and labile P of soil only at 15 DAS bean. The presence of B. brizantha cv. Marandú as cover crop increases the P content in the bean leaf with consequent grain yield gain of 18%.

Pengaruh Pupuk Kalium Dan Fosfat Terhadap Ketersediaan Dan Serapan Fosfat Tanaman Kacang Tanah (Arachis Hypogaea L.) Pada Tanah Brunizem

The aim of this research was to investigate the availability and uptake of phosphate with the application of potassium and phosphate fertilizers in brunizem soil. The experiment was arranged in a factorial completely Randomized Design which tested various levels of KCl (no calium, 0.2 g/5 kg soil and 0.4 g/5 kg soil) and SP-36 (no fosfat, 0.35 g/5 kg soil and 0.70 g/5 kg soil) fertilizers. The result showed a significant effect of potassium fertilizer treatments on soil pH. The best rate of potassium fertilizer was 0.4 g KCl per pot or 160 kg KCl ha-1. Phosphate fertilizer treatment gave a significant effect on soil pH, available phosphate and phosphate uptake. The best rate of phosphate fertilization was 0.70 g SP-36 per pot or 240 kg SP-36 ha-1.

One-time phosphate fertilizer application to grassland columns modifies the soil microbiota and limits its role in ecosystem services

This study evaluated the effect of one-time phosphate fertilization on the soil microbiota, its cycling of phosphorus (P) and grass growth. Soil columns were established in a greenhouse using a P-limited Irish soil (index 1), planted with Lolium perenne and fertilized with 0 (control), 5 (quarter), 10 (half) and 20 (full)kgPha−1 as inorganic phosphate. Only traces of phosphate in soil solution were detected over the 14week experiment, even after phosphate fertilization. Grass dry matter yield between treatments was not significantly different. Full phosphate fertilization significantly reduced the arbuscular mycorrhization (AM) rate, bacterial- and fungal-feeding nematode population, bacterial phoD gene abundance, but increased alkaline and acid phosphatase activities at the time of harvest. Full and half P treatments significantly shifted the bacterial, fungal and AM community structures compared to the control. Furthermore, the control had a significantly higher relative abundance of bacterial genera including Bacillus, Bradyrhizobium, Paenibacillus, Nocardioides and Balneimonas, that have been associated with P mobilization in the past, when compared to the full phosphate treatment. These results suggest that a positive effect of a single phosphate application on plant growth in a soil can be cancelled out by its negative effect on the soil microbiota and their ecosystem services.

Chlorella vulgaris and Pseudomonas putida interaction modulates phosphate trafficking for reduced arsenic uptake in rice (Oryza sativa L.)

Rice grown in arsenic (As) contaminated areas contributes to high dietary exposure of As inducing multiple adverse effects on human health. The As contamination and application of phosphate fertilizers during seedling stage creates a high P and As stress condition. The flooded paddy fields are also conducive for algal growth and microbial activity. The present study proposes potential role of microalgae, Chlorella vulgaris (CHL) and bacteria, Pseudomonas putida (RAR) on rice plant grown under excess As and phosphate (P) conditions. The results show synchronized interaction of CHL + RAR which, reduces As uptake through enhanced P:As and reduced As:biomass ratio by modulating P trafficking. Gene expression analysis of different phosphate transporters exhibited correlation with reduced As uptake and other essential metals. The balancing of reactive oxygen species (ROS), proline accumulation, hormone modulation, and As sequestration in microbial biomass were elucidated as possible mechanisms of As detoxification. The study concludes that RAR and CHL combination mitigates the As stress during P-enriched conditions in rice by: (i) reducing As availability, (ii) modulating the As uptake, and (iii) improving detoxification mechanism of the plant. The study will be important in assessing the role and applicability of P solubilizing biofertilizers in these conditions.

Fate of Cd in Agricultural Soils: A Stable Isotope Approach to Anthropogenic Impact, Soil Formation, and Soil-Plant Cycling.

The application of mineral phosphate (P) fertilizers leads to an unintended Cd input into agricultural systems, which might affect soil fertility and quality of crops. The Cd fluxes at three arable sites in Switzerland were determined by a detailed analysis of all inputs (atmospheric deposition, mineral P fertilizers, manure, and weathering) and outputs (seepage water, wheat and barley harvest) during one hydrological year. The most important inputs were mineral P fertilizers (0.49 to 0.57 g Cd ha-1 yr-1) and manure (0.20 to 0.91 g Cd ha-1 yr-1). Mass balances revealed net Cd losses for cultivation of wheat (-0.01 to -0.49 g Cd ha-1 yr-1) but net accumulations for that of barley (+0.18 to +0.71 g Cd ha-1 yr-1). To trace Cd sources and redistribution processes in the soils, we used natural variations in the Cd stable isotope compositions. Cadmium in seepage water (δ114/110Cd = 0.39 to 0.79‰) and plant harvest (0.27 to 0.94‰) was isotopically heavier than in soil (-0.21 to 0.14‰). Consequently, parent material weathering shifted bulk soil isotope compositions to lighter signals following a Rayleigh fractionation process (ε ≈ 0.16). Furthermore, soil-plant cycling extracted isotopically heavy Cd from the subsoil and moved it to the topsoil. These long-term processes and not anthropogenic inputs determined the Cd distribution in our soils.

Fertilizer placement and tillage effects on phosphorus concentration in leachate from fine-textured soils

Adoption of no-tillage in agricultural watersheds has resulted in substantial reductions in sediment and particulate phosphorus (P) transport in surface runoff. No-tillage, however, may result in increased losses of dissolved P in tile-drained landscapes due to the accumulation of P in surface soil layers and prevalence of preferential flow pathways. The objective of this study was to examine the effect of fertilizer placement and tillage on P leaching in fine-textured soils following fertilizer application. Rainfall simulations (90 min; 3.8 cm rainfall depth) immediately following application of monoammonium phosphate fertilizer (75 kg P ha−1) were conducted on 9 m2 plots with pan lysimeters (0.6 m depth) in four agricultural fields located in northwestern Ohio, USA. Three fertilizer placement treatments that covered a range of soil disturbance and soil-fertilizer mixing (broadcasted, injected, and tilled) were replicated on each field. Stable water isotopes were used to separate leachate into preferential and matrix flow components. Results showed that leachate dissolved P concentration was significantly greater when fertilizer was surface broadcast on no-tilled plots (43.7 mg L−1) compared to when the fertilizer was either injected (14.9 mg L−1) or tilled (11.0 mg L−1) into the soil. Event water comprised between 6 and 46% (mean = 22%) of lysimeter leachate and did not vary among treatments. Similar event water contributions among treatments suggest that the disruption of the macropore network was not likely the main mechanism responsible for decreased P concentration in leachate, but rather increased soil-fertilizer contact and decreased interaction between the highly soluble fertilizer and ponded surface water were likely responsible for decreased P concentrations observed for the injected and tilled treatments compared to the broadcasted treatment. Findings indicate that subsurface injection of fertilizer has the potential to limit dissolved P leaching compared to surface broadcast applications and also minimize soil disturbance relative to tillage; thus, it should be considered a promising conservation practice to help meet water quality goals in tile-drained landscapes.

Vertical distribution and release characteristics of phosphorus forms in the sediments from the river inflow area of Dianchi Lake, China

Columnar sediment samples were collected from five representative river inflow areas of Dianchi Lake, China. The vertical distribution of each form of P were tested. Results showed that the concentration of TP in the sediments from areas A, B, C, D and E in the order of D > B > A > C > E, and the average concentration of D, B, A, C and E were 2991, 2064, 1308, 879, and 759 mg•kg−1, respectively. The concentration of Ex-P, Fe/Al-P, Ca-P and Org-P all decreased with increasing depth. The release of Ex-P was significantly related to TP whereas the Fe/Al-P was not significantly related to TP in the samples from areas polluted by domestic sewage. However, the release of Ex-P and Fe/Al-P were both significantly related to TP in the samples from areas polluted by phosphate mining and phosphate fertilizer application. The results of equilibrium P concentration (EPC0) analysis showed that P in the sediments of areas A, D and E were the source of P in Dianchi Lake, and the P in the sediments of areas B and C were in relative equilibrium with the overlying water.

Projection Pursuit Evaluation Model of Regional Surface Water Environment Based on Improved Chicken Swarm Optimization Algorithm

A Projection Pursuit Evaluation model of surface water environment based on an Improved Chicken Swarm Optimization Algorithm (ICSOA-PPE) is constructed using the ICSOA to optimize the optimal projection direction. Using the Jiansanjiang Administration in Heilongjiang Province, China as an example, 15 subordinate farms were used as an evaluation unit by selecting water quality indexes including CODMn, NH3-N, TP, TN, F− to evaluate the environmental quality of surface water using the ICSOA-PPE model. The results show that the environmental quality of surface water from all farms in this region was generally poor, except for that at the Qinglongshan, Qindeli and Daxing farms. These three farms met the standard for drinking water sources, while the remaining farms failed to reach the standard. By analyzing the relationship between the total amount of chemical fertilizer application per ha, the amount of nitrogen fertilizer application per ha, the amount of phosphate fertilizer application per ha and the environmental quality of the surface water, a conclusion could be reached that the total amount of chemical fertilizer has a substantial effect on water environment. Additionally, the contribution rate of the amount of nitrogen fertilizer application per ha to the organic pollution and the concentration of NH3-N is substantial, and the amount of phosphate fertilizer influences the water environmental quality to some extent. An analysis and comparison of the traversal capacity, the offset capacity and the convergence capacity of the Genetic Algorithm (GA), the Chicken Swarm Optimization Algorithm (CSOA) and ICSOA reveal that ICSOA is the better optimization algorithm, indicating that the ICSOA-PPE model is logical and reliable.

Partial Nutrient Balances in Tropical Velvet Bean-Maize System in Zimbabwe

In a field experiment on legume-maize cropping sequence, the effect of nitrogen and phosphate fertiliser application on nutrient budgeting after a two year cropping cycle was studied. The results of this work showed that partial nutrient balances can give an indication about the sustainability of a system unless a full stock of all the nutrients is known. It is also clear from these results that there would unlikely be a carryover of N to the next season, probably due to leaching of N from the top soil. Positive partial P balances would, on the other hand, be of residual value. However, it should be noted that the positive partial P balances were only observed where maize yield was low. The long-term perspectives of a crop production system cannot be assessed solely on the basis of partial nutrient balances. The nutrient stock: balance ratio may be a better indicator of sustainability, giving a more accurate indication of how long farming can continue in the same way, given the available nutrients. These points towards taking a fresh look at the existing recommended application rates for maize crops.