P2O5 Rates Research Articles

Effect of Phosphorus-Containing Polymers on the Shoot Dry Weight Yield and Nutritive Value of Mavuno Grass

In an effort to improve fertility, recover degraded areas and increase support for the capacity of livestock on pasture, new forms of fertilizer are being developed. Polymer-coated monoammonium phosphate (MAP) is an innovative source of phosphorus (P) for maintaining forage grass productivity. The aim this study was to evaluate the agronomic efficiency of P rates with the presence and absence of the polymer on the productivity, development and nutritional value of hybrid signalgrass (Urochloa spp.) cv. Mavuno. The field research was conducted on a dystrophic Ultisol. The experiment was arranged in a randomized complete block design with four replications and treatments applied in a factorial scheme (2 × 4) + 1. The treatments included two P sources (uncoated MAP and polymers-coated MAP) at four rates (20, 40, 80 and 160 kg ha−1 of P2O5), and the control received no P fertilization. The measured variables showed no differences between sources with or without polymer. The maximum production of accumulated shoot dry weight yield (SDWY) of the ‘Mavuno’ grass was 20.2 Mg ha−1 with the dose of 114 kg ha−1 of P2O5. The value of crude protein and in vitro dry matter digestibility showed a quadratic response with maximum production of 76.5% and 15.9% for the P2O5 rates of 37.2 and 91.1 kg ha−1, respectively, while the acid detergent insoluble fiber showed a linear increase up to the rate of 80 kg ha−1 of P2O5. No differences were observed in plant height, number of tillers, or the relative chlorophyll content between treatments.

Nutrient Use and Management Practices on United States Golf Courses

Nutrient use on United States golf courses increases management costs and has the potential to influence ecosystems. Therefore, it is critical to assess nutrient use and management practices to develop and teach best management practices. The objectives of this survey were to measure nutrient use and management practices on United States golf courses in 2021, and to determine if changes occurred since 2006. A survey was developed and distributed via e-mail to 14,033 United States golf facilities, with 1444 responding. From 2006 to 2021, the total projected nitrogen (N), available phosphorus (P2O5), and soluble potash (K2O) applied declined by 41%, 59%, and 54%, to 54,376, 13,761, and 41,386 tons, respectively. These reductions were attributed to course closures, reduced fertilized acres, reduced application rates, and nutrient use restrictions. The percentage of facilities that did not apply P2O5 increased to 21%, which is likely a result of P2O5 application restrictions. Soil testing was associated with greater application rates of N, P2O5, and K2O. Returning clippings, using precision fertilizer applications, reducing turfgrass acreage, and considering N release from soil organic matter were associated with reduced application rates of P2O5. Golf course superintendents have contributed to nationwide reductions in N, P2O5, and K2O, as evidenced by the reduction in fertilized acres and the reduction in nutrient use rates from 2006 to 2021.

Study on the recovery of phosphorus and iron from molten modified high-phosphorus industrial slag by carbothermal reduction

To effectively recycle phosphorus and iron resources in high-phosphorus industrial slag during molten modification process, the thermodynamic conditions and influence laws of recovery of valuable elements from converter slag with different P2O5 content by carbothermal reduction after melting and modification are systematically analyzed. The results show that the reduction rates of P2O5 and FeO decrease with the increase of P2O5 content at 1450 °C and the basicity of 1.0. Meanwhile, the experimental results prove that the reduction of FeO precedes the reduction of P2O5.The phosphorus element in initial industrial slag mainly exists in the form of Ca5(PO4)2SiO4 and increases with the increase of P2O5 content. With the progress of the carbothermal reduction reaction, the Ca5(PO4)2SiO4 content in experimental slags after reduction decrease significantly. The iron element in initial industrial slag mainly exists in the form of FeO, (MgO)0.239 (FeO)0.761 and Ca2Fe2O5 and disappear after carbothermic reduction reaction. In the range of P2O5 content of 4–8 wt.%, P2O5 content has little effect on the thermodynamic trend of the formation of phosphorus-containing phase Ca5(PO4)2SiO4, but it is not good for the thermodynamic trend of gasification dephosphorization reaction in the carbothermic reduction process. Therefore, the increase of P2O5 content is not conducive to the occurrence of carbothermic reduction gasification dephosphorization reaction.

Gypsum in Improving the Use of Phosphate Fertilization for Soybean Crops

ABSTRACT The improvement of the chemical conditions of the soil in the subsurface is indicated as an alternative to increasing soybean yields because it is related to greater efficiency of water and nutrient use, such as phosphorus (P). The study aimed to evaluate the soil chemical changes and the soybean yield due to the application of P and gypsum. For this, a field experiment was conducted between 2017 and 2020 under a Humic Cambisol in Southern Brazil. The treatments were composed of four corrective rates of P2O5 (0, 50, 100, and 200 kg ha−1) associated or not with agricultural gypsum (0 and 1400 kg ha−1). In the first year of evaluation, there was an increase in soybean yield with gypsum, and rates of P. In the absence of P correction, root length density was higher in the 20–30 cm layer. There was a linear increase in P available in the topsoil (0–10 cm) as a function of the nutrient rate. With gypsum application, there was an increase in calcium (Ca) and reduction of magnesium (Mg) in the 0–10 cm layer, besides the increase of sulfate (S-SO4 2-) in all layers. The application of agricultural gypsum promotes chemical changes in the soil at depths of up to 40 cm and gains in soybean yield, even without altering the efficiency of P use by plants.

Physical and physicochemical characteristics of tomato fruits grown under different irrigation water levels and phosphorus sources and rates

Phosphorus (P) is one of the most limiting nutrients for growth and development of crops, and is important for soil fertility managements, since it affects the quality of fruits. With the hypothesis that different levels of irrigation and phosphorus fertilization interfere in the physical and physicochemical properties of tomatoes, the objective of this experiment was to verify this hypothesis and analyze the behavior of the fruits’ responses. The experiment was conducted in a greenhouse at the Hydraulic and Irrigation Laboratory of the Federal Institute of Education, Science, and Technology of the State of Goiás, in Rio Verde, Goiás, Brazil. A randomized block design was used, with a 4×2×4 split-plot arrangement and three replications, totaling 96 experimental plots. The treatments consisted of four P2O5 rates: 25%, 50%, 100%, and 200% of the recommended rate; two P sources: monoammonium phosphate (MAP) and organo-mineral (OM); and four IWL: 50%, 75%, 100%, and 125% of the field capacity. The fruits were evaluated for longitudinal (FLD) and transversal (FTD) diameters, potential hydrogen (pH), titratable acidity (TA), total soluble solid (TSS) contents, and TSS to TA ratio (TSS/TA). The effect of the interactions between the factors IWL and P rate, IWL and P source, and P rate and source were significant for FLD and FTD, TSS, TA, and TSS/TA. The effects of the interactions between IWL and P rate, and IWL and P source were significant for pH. The MAP source combined with the rate of 25% and IWL of 125% resulted in tomato fruits with larger FLD and FTD. The rate of 25% combined with IWL of 77% and 100% resulted in tomato fruits with higher TSS and pH. The OM source resulted in tomato fruits with higher TA when combined with IWL of 50%, and larger FLD when combined with IWL of 105% and 125%.
 (This article belongs to the Special Issue: Agricultural Water Management in Arid and Semi-arid Regions)

EVALUATION OF FOUR PROMISING BREAD WHEAT GENOTYPES TO DIFFERENT PHOSPHORUS LEVELS FOR YIELD AND ITS COMPONENTS

The study was done during winter season 2020-2021 at field of College of Agricultural Engineering Sciences, Duhok University, to evaluate the influence of different phosphorus fertilizer P2O5 rate (0, 60, 90, 120kg ha-1 on yield and yield components of four promising bread wheat Bura, Jehan-99, Apst-35 and Apst-26. The experiment was Laid out in factorial experiments using randomize complete block design with three replications. Significant difference in plant height, flag leaf area (cm), spike length(cm), No. seed spike, weight of seed per spike, 1000-seed weight and total yield were observed by the application of different phosphorus fertilizer 120kg ha-1. However, only days to 75% flowering was not significant affected by different rate of phosphorus fertilizer. Also the results exhibited that the Apast-35 was significant in plant height (104.91cm), flag leaf area (40 cm2), spike length (15.4cm), No. seed per spike (37), seed weight of spike (1.48g), 1000-seed weight (41.09g) and total yield 3.66 (t.ha-1). The simple correlation exhibited positive and significant between yield and plant height (0.89), leaf area (0.85), 1000-seed weight (0.76), No. seed per spike (0.87) and weight of seed spike (0.92), this main these traits were intributed to increase the yield under rate 120kg ha-1of phosphorus P2O5.

Inoculation with Plant Growth-Promoting Bacteria to Reduce Phosphate Fertilization Requirement and Enhance Technological Quality and Yield of Sugarcane.

Phosphorus (P) is a critical nutrient for high sugarcane yields throughout its cultivation cycles, however, a higher amount of P becomes rapidly unavailable to plants due to its adsorption to soil colloids. Some plant growth-promoting bacteria (PGPBs) may be able to enhance P availability to plants and produce phytohormones that contribute to crop development, quality, and yield. Thus, this study aimed to evaluate leaf concentrations of nitrogen (N) and P, yield, and technological quality of sugarcane as a function of different levels of phosphate fertilization associated with inoculation of PGPBs. The experiment was carried out at Ilha Solteira, São Paulo—Brazil. The experimental design was randomized blocks with three replications, consisting of five phosphorus rates (0, 25, 50, 75, and 100% of the recommended P2O5 rate) and eight inoculations, involving three species of PGPBs (Azospirillum brasilense, Bacillus subtilis, and Pseudomonas fluorescens) which were applied combined or in a single application into the planting furrow of RB92579 sugarcane variety. The inoculation of B. subtilis and P. fluorescens provided a higher concentration of leaf P in sugarcane. The P2O5 rates combined with inoculation of bacteria alter technological variables and stalk yield of sugarcane. The excess and lack of phosphate fertilizer is harmful to sugarcane cultivation, regardless of the use of growth-promoting bacteria. We recommend the inoculation with A. brasilense + B. subtilis associated with 45 kg ha−1 of P2O5 aiming at greater stalk yield. This treatment also increases sugar yield, resulting in a savings of 75% of the recommended P2O5 rate, thus being a more efficient and sustainable alternative for reducing sugarcane crop production costs.

Nutrient Accumulation Affected by Corn Stover Management Associated with Nitrogen and Phosphorus Fertilization

Bio-ethanol production from corn stover harvest would change nutrient removal, in particular nitrogen (N) and phosphorus (P), affecting nutrient replenishment and corn development under field-grown conditions. This research was developed to investigate whether stover removal had any influence on the amount of N and P fertilizer required for maximum corn production in the United States (US) Midwest in a stover removal scenario. This study was conducted in Lamberton, MN on a Typic Endoaquoll under continuous corn from 2013 to 2015. The treatments included six N rates (0 to 200 kg N ha−1 in 40 kg increments), five P rates (0 to 100 kg P2O5 ha−1 in 25 kg increments), and two residue management strategies (residue removed or incorporated). Residue management was found to have a significant impact on corn response to N and P application. We verified that residue-removed plots yielded more and therefore required more N and P application from fertilizers. Grain yield after residue was removed was greatest with the highest N and P2O5 rates, whereas grain yield after residue was incorporated was greatest with intermediate N and P2O5 rates in 2013 and 2014. In 2015, residue management did not significantly affect grain yield. Grain N and P accumulation followed a similar behavior as that observed for grain yield. In general, residue removal decreased nutrient availability, while in the residue-incorporated treatment, those nutrients were returned. Although the results of the study showed potential for biomass harvest, it also indicated that nitrogen immobilization and nutrient depletion from the soil could be a limiting factor.

Effect of Phosphorus Application Methods on Growth and Yield of Maize under Water Deficit Conditions

A field study was conducted to investigate effect of phosphorus and different levels of irrigation on growth and yield of maize at the Agronomic Research Area, Faculty of Agricultural sciences and Technology, Bahauddin Zakariya University, Multan, during autumn 2016.The Experiment was laid out in randomized complete block design (RCBD) with split plot courses of action having three replications with net plot size of 4m x 3m. The crop was sown in 75 cm spaced rows, while plant to plant distance was maintained at 30 cm with the help of dibbler. Experimental treatments comprised of two irrigation level sand four phosphorus levels. The crop was harvested at maturity and the data were recorded by using the standard procedures. Maximum grain yield was obtained at full irrigation levels where phosphorus was applied @ 100 kg ha-1. All the growth and yield parameter increased with full irrigation levels with application of Phosphorus at the rate of 100 kg ha-1 while it was decreased where half irrigation was applied. Increase in P2O5 rates upto100 kg ha-1 enhanced the plant height, cob length, cob weight, thousands grain weight, Beyond application of 100 kg P2O5 ha-1 there was no significant increase in number of grains cob-1, thousand grain weight and other growth parameters. It is recommended that maize crop should preferably be fertilized @ 100 kg Phosphorus per hectare to get maximum grain yield under the ecological conditions of Multan.

Corn yield response to phosphorus and potassium fertilization in Arkansas

AbstractPhosphorus and potassium are key nutrients for plant physiological processes and are required in large amounts for adequate corn (Zea mays L.) production. Corn is a major row crop, and up‐to‐date soil test‐based fertilizer recommendations are required to enhance production and profitability. The results from 32 P and 42 K field trials evaluating irrigated corn response to fertilizer P and K rates were used to (i) correlate corn's relative yield response to Mehlich‐3 soil test P and K, (ii) determine the frequency and magnitude of the yield response to fertilization, and (iii) calibrate fertilizer P and K rates to soil test P and K. The quadratic and linear models identified 36 parts per million (ppm) P (r2 = .68, P < .0001) and 110 ppm K (r2 = .36, P < .0001) as the Mehlich‐3 soil test P and K values needed to produce 95% of maximum yield without fertilization. Additional research is needed on soils with P < 15 and > 35 ppm and K < 60 and > 120 ppm to enhance the scope of data in the analyses and improve our understanding of corn's response to P and K fertilization. The current thresholds defining soil test K levels perform well in interpreting soil K availability and corn's response to K fertilization. Mehlich‐3 soil test P level definitions should be modified to improve the accuracy of soil test‐based decisions for irrigated corn. The calibration results suggest the recommended P2O5 and K2O rates are greater than needed to maximize yield.

Phosphate Fertilizer in Soybean-Wheat Cropping System Under No-Till Management

IImprovements in soybean (Glycine max [L.] Merrill) and wheat (Triticum aestivum L.) yields in cropping systems under no-till management (NTM) in the subtropics have been obtained through advances in phosphorus (P) utilization, cultivar selection, and planting and harvesting strategies. This fact, along with the P application in band application in consolidated planting, has resulted in lower P utilization efficiency and depleted soil P levels. The aim of this study was to evaluate the efficiency of P2O5 rates and application methods in soybean-wheat cropping under NTM during two growing seasons (2014–2016) in a Typic Eutrorthox. Four P2O5 rates (0, 30, 60, and 120 kg ha-1) of triple superphosphate (45% P2O5) were applied using two application methods (broadcast and band application at sowing) before the soybean and wheat crops were cultivated. Both P application methods resulted in a significant yield response to P2O5 rates for the soybean and wheat crops. Under NTM, broadcast P2O5 application was more effective than band application in soybean, and maximum grain yields were obtained with 129.3 and 88.1 kg P2O5 ha-1, respectively. Maximum wheat grain yields were obtained with 91.8 and 99.7 kg P2O5 ha-1 for broadcast and band application, respectively. Except for total P in leaves, nutrient uptake and yield components were not affected by the P application methods and rates. The results suggested that in soils with adequate available P levels of >15 mg kg-1 (Mehlich 1 extractant), the grain yield is equivalent or superior with broadcast P application as compared to band application for both soybean and wheat crops when cultivated in a Typical Eutrorthox under subtropical conditions. However, broadcast application is considered more effective for large areas of grain cultivation, where it is necessary to sow crops uniformly within the shortest possible time.

Path Analysis between Pest Occurrence and Nutritional Status of Soybean under Phosphate Fertilization.

The phytophagous insects select their host plants according to plant tissue nutritional quality. Thus, the objective of this study was to correlate the direct and indirect effects of phosphate fertilization on the nutritional status of the soybean crop and its relationship with the occurrence of insect pests. The effect of phosphate fertilization on soybean was evaluated using two phosphate sources, Single Superphosphate (SSP) and Monoammonium Phosphate (MAP), applied at five rates of P2O5. A sampling of insects initiated from stage V5 and was done weekly. Leaves were collected for nutrient analysis stage R1, in stage R9 was harvest was carried out. SSP or MAP phosphate fertilization in soybean affected the incidence of Chrysodeixis includens, Helicoverpa armigera, Elasmopalpus lignosellus and Euschistus heros. The plants treated with MAP had the infestation reduced compared with plants treated with SSP. Higher contents of Cu and Fe in the leaf reduces the incidence of insect-pests, whereas the opposite occurred with Mn. The occurrence of E. lignosellus reduced soybean yield. Therefore, the source and rates of phosphorus in soybean fertilization change the concentration of macro and micronutrients in the leaves and affect the behavior and incidence of pest species.

Corn Yield and Phosphorus Use Efficiency Response to Phosphorus Rates Associated With Plant Growth Promoting Bacteria

The use of plant growth promoting bacteria that can solubilize phosphorus (P) has shown potential to improve nutrient availability in grass crops such as corn (Zea mays L.) This study was developed to investigate if inoculation with Azospirillum brasilense, Bacillus subtilis or Pseudomonas fluorescens associated with P2O5 rates can improve phosphorus use efficiency (PUE) reflecting on greater corn development and yield. The field trial was set up in a Rhodic Hapludox under no-till system under Savannah conditions, in a completely randomized block design with four replicates. Treatments were tested in a full factorial design and included: i) five P2O5 rates (0 to 105 kg ha-1) and ii) four PGPB seed inoculation (Control – without inoculation, A. brasilense, B. subtilis or P. fluorescens). Inoculation was found to increase grain yield by 17.5% when B. subtilis was inoculated associated with 70 kg P2O5 ha-1 and by 34.7% when A. brasilense was inoculated with application of 105 kg P2O5 ha-1. In addition, inoculation with B. subtilis and A. brasilense were found to increase biomass and grain P uptake, number of grains per row, stem diameter, ear length and PUE. The results of this study showed positive improvements in P uptake as a result of B. subtilis and A. brasilense inoculation, with an increase of 86.9 and 40.6% on PUE, respectively; while the P. fluorescens inoculation were less evident. Further research should be conducted under biotic or/and abiotic conditions to better understand the role of PGPB, inoculated alone or in combination as the co-inoculated method.

Banana fruits with high content of resistant starch: Effect of genotypes and phosphorus fertilization

Banana fertilization practices aim to increase agricultural yield and the effects of these practices on fruit components have not been well explored. This study aimed to evaluate the effects of phosphate fertilizer levels on production parameters and accumulation of dry matter, phosphorus, starch and resistant starch in green fruits. Four banana genotypes were cultivated under the same cultural practices, with varying levels of phosphate fertilizers during three production cycles. Bunches were harvested and evaluated for total fruit mass, average finger mass and yield. Fresh green fruit pulps were analyzed for dry matter, phosphorus, starch and resistant starch content. The results showed that the effects of phosphate fertilizer were genotype dependent and that the increase of P2O5 rates applied in banana fertilization promoted an increase in fruit production with higher levels of phosphorus, starch and resistant starch.

Potato (Solanum tuberosum L.) Tuber Yield and Yield Components as Influenced by Different Levels of Nitrogen, Phosphorus and Potassium in Rwanda

Despite potato yield potential, its intensification level remain low in Rwanda, translating into low yield occasioned mainly by the decline in soil fertility. Field experiments were conducted in Birunga, Mudende [L1]) and Buberuka, Rwerere [L2] highlands Agro-Ecological Zones (AEZs), during September- December 2016 and March-June 2017 crop growing seasons to determine the effects of varying rates of N, P and K on potato tuber yield and yield components. The experiments were laid out using randomized complete block design with factorial arrangement, with four replicates. Factors were N rates (NX) i.e N1-0 kg ha-1, N2 – 50 kg ha-1, N3 – 100 kg ha-1 ; P2O5 rates (PX) i.e P1-0 kg ha-1, P2 – 50 kg ha-1, P3 – 100 kg ha-1and K2O rates (Kx) i.e K1- 0 kg ha1and K2- 50 kg ha-1. Number of tubers per plant, fresh tuber weight, small tuber yield, medium tuber yield, large tuber yield and total tuber yield were measured. Analysis of variance, performed using SAS-version 9.2, revealed that interaction effects of N×P×K were very highly significant on all parameters. Generally, N3×P3×K2 performed better than other treatments and recorded highest tuber yields in all situations: (32.73 ± 0.43) t ha-1[L1] and (29.36 ± 0.41) t ha-1 [L2] and (31.05 ± 0.52) t ha-1for pooled ANOVA. Contrarily to what happened at L2, N3P3K2 andN2P3K2 were not significantly different at L1. N2P3 K2 is recommended to L1 whereas N3P3K2 is recommended to L2.

Tuber yield and economic result of ‘Atlantic’ potato in response to NPK fertilizer formulas

ABSTRACT The usual application of high 4-14-8 NPK fertilizer rates in the potato planting furrows, independently of the soil fertility or nutritional cultivar requirements, has become a paradigm in Brazil. However, the 4-14-8 NPK formula does not always meet the crop needs, and can unbalance the availability of nutrients in the soil. The objective of this study was to evaluate the tuber yield and economic results of ‘Atlantic’ potato as affected by rates of 4-14-8 and 6-30-6 NPK formulas applied in the planting furrows. The rates of both NPK formulas were calculated to reach P2O5 rates of 210, 420, and 630 kg ha-1. At each P2O5 rate, the 6-30-6 formula resulted in less 30% N and 65% K2O in the planting furrow compared to 4-14-8 formula. A randomized complete block design in a factorial scheme (2×3)+1, including an unfertilized furrow control, with three replications was used. Only the use of 6-30-6 formula increased the total tuber yield of ‘Atlantic’ potato. The marketable tuber yield reached higher levels (29.8 t ha-1) with higher P2O5 rate (440 kg ha-1) using the 6-30-6 than 4-14-8 formula. The fertilizer rates and formulas NPK did not affect specific gravity of marketable tubers. Therefore, the use of a fertilizer more concentrated in P2O5 that favors smaller contributions of N and K (as the 6-30-6 formula studied in this work) provides lower costs, and greater operational efficiency and profits in relation to the 4-14-8 formula traditionally used for the potato crop.

Forms of application of phosphorus fertilization on carrot

The aim of this study was to evaluate the effect of forms of application and application rates of phosphate fertilizer on the agronomic characteristics of carrot. A field experiment was carried out in a 2 × 7 factorial arrangement, consisting of two forms of application of the P source (over the whole area or specifically in the strip of the double row), and seven application rates of P2O5 in randomized blocks, with four replicates. Shoot dry matter yield increased linearly, and root dry matter yield increased exponentially with an increase in P rate. Total and commercial yields increased exponentially, with higher yield for P application over the whole area. However, the agronomic efficiency for site-specific application was higher. Higher rates of P application caused increases in the soil attributes and technical traits of carrot, and the application of phosphorus fertilizer is more efficient when performed in a site-specific manner.

Modeling in the Adjustment of Fertilization Recommendation through Leaf Analysis in Fertigated ‘Prata’ Banana

ABSTRACT: In banana cultivation, fertilization recommendations are almost exclusively based on soil chemical analysis, without considering leaf analysis and expected yield, which can help in the adjustment of fertilization programs. The aim of this study was to develop a method to recommend macronutrient fertilization rates which integrates data on leaf analysis, soil chemical analysis, and yield. Yield, soil chemical analysis, and leaf analysis data of fertigated plantations of ‘Prata’ banana were obtained for the first and second halves of the years from 2010 to 2015. Yield was correlated with soil organic matter (SOM) and soil contents of macronutrients (P, K, Ca, and Mg) to obtain the critical level (CLNui). Then, leaf nutrient contents were plotted on a dispersion graph as a function of soil contents using the method of Quadrant Diagram of the Plant-Soil Relationship (QDpsR). Based on leaf analysis, recommended rates were simulated for four plots and compared with rates recommended by other methods. The values of CLNui obtained were 13.2 g dm−3for SOM; 97.5 and 91.5 mg dm−3for P and K; and 2.71 and 0.61 cmolc dm−3for Ca2+and Mg2+. The rates recommended based on leaf analysis diverged from the recommendations of Ferticalc®-Bananeira and the Recommendation Table for Banana Fertilization; in plots for which recommendations were made, there were higher rates of P2O5 and Ca and lower rates of K2O. However, in most cases, applications were not recommended, either because contents in leaves and soil were adequate or because yield was being limited by non-nutritional factors or, if nutritional, related to other nutrient(s). Leaf analysis satisfactorily adjusts the recommended rates of nutrients and has advantages if incorporated in nutritional balance models.

Chickpea production and soil chemical attributes after phosphorus and molybdenum fertilization

ABSTRACT Chickpea is the third most cultivated legume in the world. In Brazil, cropping of this legume is recent and definitions of fertilizer management techniques are scarce. In this study, the objective was to evaluate chickpea (BRS Aleppo) production and soil chemical attributes with and without phosphorus fertilization and leaf-applied molybdenum. A randomized block experimental design was used, with four replications. A 2 x 5 factorial arrangement was used to evaluate production, consisting of two molybdenum fertilization management practices (with and without molybdenum) and five application rates of P2O5 (0, 60, 120, 180, and 240 kg ha-1) in the form of single superphosphate. Soil sampling for evaluation of soil chemical attributes in the crop row and between rows was also considered. Molybdenum fertilization brought about greater stem and aboveground dry matter. Phosphorus fertilization increased stem, leaf, and seed yield, yielding a maximum of 2.83 t ha-1 seed at the rate of 200 kg ha-1 P2O5. However, maximum agronomic efficiency (8.30) was observed with the addition of 150 kg ha-1 P. Soil in the crop row attained higher concentrations of P, K, H+Al, and P-rem and reduction in pH, Ca concentration, SB, T, and V compared to between rows. Phosphorus rates reduced soil pH and increased T and the P concentrations, though only in the plant row. Between the rows, no changes were observed in soil chemical attributes, indicating low mobility of P and the acidification capacity of superphosphate in alkaline soils.

Effect of Phosphorus Levels on Soil Properties and Plant Tissues of Two Nerica Varieties

Phosphorus levels in the soil are easily fixed and rendered unavailable to plants even if they are found to be high and therefore, its influence on uptake of other nutrients such as nitrogen, and potassium cannot be overemphasized. In that view, an experiment was set out at KALRO-Mwea to investigate on the effect of phosphorus levels on soil properties and plant tissue nutrient contents of Nerica rice variety. The experiment was laid out in a Randomized Complete Block Design in split-split plot arrangement and replicated thrice. Two rice varieties (Nerica 11 and Nerica 4) formed the main plots and 4 phosphorus levels (0 kg P/ha, 25 kg P/ha, 50 kg P/ha and 75 kg P/ha) formed the sub plots. Highest net pH decreases of 0.20 and 0.22 units were recorded at 75 Kg haˉ¹ P2O5 in season 1 and season 2 respectively, while the lowest net decreases of 0.12 and 0.16 were elicited at 50 Kg haˉ¹ P2O5 treatment in season 1 and season 2 respectively. A net decrease was observed in all the CEC levels where phosphorus was applied in all the seasons in which the highest net decrease of 1.09 and 1.03 during season 1 and 2 respectively was elicited on the control treatment, while the lowest net decrease of 0.61 and 0.59 was elicited by the 50 Kg haˉ¹ P2O5 rate in season 1 and 2 respectively. There was an inverse relationship exhibited between the phosphorus level of applications and the soil phosphorus net decrease across the two seasons. The net decrease was highest at 0 Kg haˉ¹ P2O5 and increased significantly with increasing phosphorus rate. That content of soil nitrogen were low with a marginal increase recorded with application of phosphorus across the seasons. The highest net increase of 0.05% was observed at the 75 Kg haˉ¹ P2O5 rate and control in season 1 while the application rate of 50 Kg haˉ¹ P2O5 had the lowest net increase of 0.02% in season 2. Highest mean plant-tissue phosphorus of 62.05 ppm was recorded in Nerica 4 under 75 kg P/ha treatment. Highest plant tissue nitrogen of 0.686% and 0.713% for Nerica 4 and 11 respectively were elicited at 75 kg haˉ¹ P2O5 in season 1, whereas in season 2 the highest plant tissue nitrogen of 0.721% and 0.691% at 75 kg haˉ¹ P2O5 for Nerica 11 and 4 respectively was recorded. Application of phosphorous led to the highest plant-tissue phosphorus in both seasons indicating the importance of proper P fertilizer application where from this study 50-75 kg haˉ¹ P2O5 rate is recommended in rice growing.