Triple Superphosphate Fertilizer Research Articles

Evaluating the agronomic efficiency of alternative phosphorus sources applied in Brazilian tropical soils

Understanding the efficacy of alternative phosphorus (P) sources in tropical soils is crucial for sustainable farming, addressing resource constraints, mitigating environmental impact, improving crop productivity, and optimizing soil-specific solutions. While the topic holds great importance, current literature falls short in providing thorough, region-specific studies on the effectiveness of alternative P sources in Brazilian tropical soils for maize cultivation. Our aim was to assess the agronomic efficiency of alternative P sources concerning maize crop (Zea mays L.) attributes, including height, shoot dry weight, stem diameter, and nutrient accumulation, across five Brazilian tropical soils. In greenhouse conditions, we carried out a randomized complete block design, investigating two factors (soil type and P sources), evaluating five tropical soils with varying clay contents and three alternative sources of P, as well as a commercial source and a control group. We evaluated maize crop attributes such as height, dry weight biomass, and nutrient accumulation, P availability and agronomic efficiency. Our results showed that, although triple superphosphate (TSP) exhibited greater values than alternative P sources (precipitated phosphorus 1, precipitated phosphorus 2 and reactive phosphate) for maize crop attributes (e.g., height, stem diameter, shoot dry weight and phosphorus, nitrogen, sulfur, calcium and magnesium accumulation). For instance, PP1 source increased nutrient accumulation for phosphorus (P), nitrogen (N), and sulfur (S) by 37.05% and 75.98% (P), 34.39% and 72.07% (N), and 41.94% and 72.69% (S) in comparison to PP2 and RP, respectively. Additionally, PP1 substantially increased P availability in soils with high clay contents 15 days after planting (DAP), showing increases of 61.90%, 99.04%, and 38.09% greater than PP2, RP, and TSP. For Ca and Mg accumulation, the highest values were found in the COxisol2 soil when PP2 was applied, Ca = 44.31% and 69.48%; and Mg = 46.23 and 75.79%, greater than PP1 and RP, respectively. Finally, the highest values for relative agronomic efficiency were observed in COxisol2 when PP1 was applied. The precipitated phosphate sources (PP1 and PP2) exhibited a similar behavior to that of the commercial source (TSP), suggesting their potential use to reduce reliance on TSP fertilization, especially in soils with low clay contents. This study emphasized strategies for soil P management, aimed at assisting farmers in enhancing maize crop productivity while simultaneously addressing the effectiveness of alternative P sources of reduced costs.

Parsley production using organic sources of phosphorus

Parsley is a condiment produced mainly by small producers, often in the organic system. Organic fertilizers make nutrients slowly available to plants when compared to inorganic fertilizers, an important quality for phosphorus (P), which is a nutrient that tends to fixate and adsorption. Thus, the objective of this work was to evaluate the production of parsley with the use of organic sources of phosphorus in different proportions. Fourteen treatments were evaluated, resulting from the factorial 6 x 2 + 2: six proportions of two phosphate fertilizers (thermophosphate Yoorin® (TY) and bone meal (BM)), two doses (recommended (180 kg.ha-1 of P2O5, and double this) + two controls (without phosphate fertilizer; and with inorganic triple superphosphate fertilizer (recommended dose)). The proportions were: 100% P with TY; 80% P with TY + 20% with BM; 60% P with TY + 40% with BM; 40% P with TY + 60% with BM; 20% P with TY + 80% with BM; 100% P with BM. Shoot height, number of leaves, fresh and dry weight of leaves in two harvests and the total of these two harvests were evaluated. No significant differences were obtained in the two harvests. The lack of effect to phosphate fertilization may be related to the high initial P content in the soil (123 mg.dm-3), which shows that in this case, fertilization with this nutrient is not necessary to produce parsley, despite the official recommendation to fertilize with phosphorus in a soil with a high P content.

Unexpectedly, triple super phosphate fertilizer induces maize drought resilience

Phosphorus fertilizer is commonly applied to soils in crop production as diammonium phosphate (DAP). To decrease ammonium addition to the environment, triple super phosphate (TSP) is being considered as a DAP replacement. This study was undertaken to compare the response of maize plants to soil fertilization with TSP vs. DAP under well-watered conditions, under soil-drying conditions, and root hydraulic conductance. It was found for well-watered conditions in a controlled environment that there was no difference in plant growth between DAP to TSP treatments. In soil dry-down experiments, however, the initiation of the decrease in transpiration rate was unexpectedly quite different between DAP and TSP treatments. The soil water content threshold for initiation of decrease in transpiration rate with DAP treatment (average fraction transpirable soil water for two experiments = 0.285) was consistent with common observations, but the threshold associated with TSP treatment occurred at an unusually high soil water content (average fraction transpirable soil water for two experiments = 0.545). The higher threshold with TSP resulted in an extended period of soil water use, i.e. soil water conservation. Soil water conservation resulting from the TSP treatment was associated with a 27% greater shoot mass accumulation following a 4-wk re-watering period after the water-deficit treatment than measured with the DAP treatment. The high threshold for decrease in transpiration resulting from TSP was consistent with measured lower root hydraulic conductance as compared to DAP treatment. The unexpected discovery of TSP-induced initiation of transpiration rate decrease at high soil water content is consistent with greater crop drought resilience.

Assessment of radioactivity level and associated radiological hazard in fertilizer from Dhaka.

Miners, factory workers, traders, end-users, and foodstuff consumers all run the risk of encountering health hazards derived from the presence of elevated levels of radiation in fertilizers, as these groups often come into direct or indirect contact with fertilizers as well as raw materials throughout various linked processes such as mineral extractions, fertilizer production, agricultural practices. A total of 30 samples of various kinds of fertilizer produced in different factories in Dhaka megacity were analyzed to quantify the concentrations of primordial radionuclides using HPGe detector. Among the analyzed samples, average (range) concentration of 40K was found to be 9920 ± 1091 (8700 ± 957-11,500 ± 1265), 9100 ± 1001 (8600 ± 946-9600 ± 1056), 2565 ± 282 (2540 ± 279-2590 ± 285), and 3560 ± 392 (2620 ± 288-4500 ± 495) Bq/kg in the samples of Muriate of Potash Fertilizer, Sulphate of Potash Fertilizer, Humic Acid Fertilizer, and NPKS Fertilizer, respectively. Elevated concentration of 226Ra was found in Triple Super Phosphate Fertilizer with a mean (range) of 335 ± 37 (290 ± 32-380 ± 42) Bq/kg. The higher activity of 40K can be linked to the greater levels of elemental potassium in phosphate fertilizer. Elevated concentrations of radionuclides may also result from variations in chemical processes as well as the local geology of the mining areas where the raw materials were extracted for fertilizer production. Numerous fertilizer brands surpass prescribed limits for various hazardous parameters, presenting significant health risks to factory workers, farmers, and consumers of agricultural products. This study provides baseline information on the radioactivity of fertilizers, which could be used to develop mitigation methods, establish national fertilizer usage limits, justify regulatory frameworks, and raise public awareness of fertilizer overuse. The findings of the study could potentially help to explore the impact of fertilizer on the food chain.

Effect of adding CaCO3 and triple superphosphate fertilizer on growth and the content of alizarin of Rubia tinctorum L. in field conditions

Effect of adding CaCO3 and triple superphosphate fertilizer on growth and the content of alizarin of Rubia tinctorum L. in field conditions

Metabolic and transcriptomic effects of Aphanothece sp. biostimulant on tomato plant growth and phosphorus acquisition

AbstractBackgroundPhosphorus (P) fertilizers, made from rock phosphate, increase crop yields. However, rock phosphate is a finite resource, stressing the need for more P‐efficient crops.AimsThis study aims to exploit P‐adaptive traits that enhance P‐acquisition and P‐use efficiency in crops, as a potential sustainable P‐use management method in agricultural settings.MethodsThis study investigates the biostimulant effects of Aphanothece sp. extracts (ApE) on P absorption efficiency traits of tomato plants supplied with triple super phosphate fertilizer (0.3, 0.6, and 1.2 mM Pi).ResultsApE extracts exhibited significant effects on P uptake, Lycopersicum esculentum high‐affinity phosphate transporter (LePT) genes, chlorophyll, and lipid contents, compared with control plants. ApE significantly enhanced leaf LePT4 in ApE‐treated plants supplied with 0.3 mM Pi, and root LePT2 in ApE‐treated plants supplied with 0.6 mM Pi. According to principal component analysis, P concentration in roots (root Pi) was closely associated with root dry weight (DW), root LePT2, and leaf LePT4. The phytohormone, gibberellin gibberellic acid 4, slightly correlated with root Pi, LePT2 (0.18), LePT4 (0.28), and more with root (0.72) and shoot DW (0.60), whereas abscisic acid correlated with chlorophyll content (0.60), LePT2 (0.50), and LePT4 (0.49), and slightly with root Pi (0.22). Gas chromatography–mass spectrometry analysis also showed that the application of ApE to plants stimulated the biosynthesis of several metabolites. The metabolic pathway analysis using MetaboAnalyst revealed that ApE treatment induced the unsaturated fatty acid, steroid, cutin, suberin, and wax biosynthesis pathways.ConclusionsApE application to tomato plants stimulated P uptake by roots through enhanced expression of high‐affinity P transporters (root LePT2 and leaf LePT4), positively correlated with root DW and root Pi. The study also suggests that algal extracts stimulate plant growth through improved P uptake and modulate the plant's metabolic pathways that favor crop performance in tomato plants under normal Pi conditions.

Potential Use of Phosphate-Solubilizing Bacteria in Soybean Culture

Using microorganisms to enhance crop productivity is an active and increasing field of research, which encompasses the productive, environmental, and economic aspects of agricultural production to obtain high-quality crops with a reduction in the need for fertilizers. Among the nutrients necessary for plant growth, phosphorous is problematic due to its low availability and its susceptibility to convert into non-labile forms. In this regard, phosphate-solubilizing bacteria (PSB) can be an interesting tool to improve phosphorous availability and to reduce the requirements of phosphate fertilizers. This work aimed to evaluate the potential use of phosphate-solubilizing bacteria in the supply of phosphorus and soybean development. This study was conducted in the 2019/2020 and 2020/2021 harvests. The experimental design was in randomized blocks, containing seven treatments and six replicates. The treatments consisted of five doses of phosphate fertilization, using triple superphosphate fertilizer, associated with the application of Bacillus subtilis and Bacillus megaterium bacteria, and two treatments, with and without the use of phosphorous fertilizer and without the use of an inoculant. Plant tissue nutrients and biometric and productive parameters of the crop were assessed. According to the observed results, applying PSB associated with phosphate fertilization and phosphate fertilization alone did not influence soybean’s nutritional, biometric, and productive parameters in the two harvests. Thus, the application of B. subtilis and B. megaterium, either associated or not associated with phosphate fertilization, does not contribute to the nutrition, development, and yield of soybean crops in soil with a naturally low P content, considering the climatic and soil conditions of the study.

Establishing phosphorus critical values for tomato (Solanum lycopersicum) fertilization with phosphate fertilizers on the Sudan savanna soils using three soil phosphorus extraction methods and field experimentation in Kano State, Nigeria

Phosphorus (P) is an essential nutrient for tomato (Solanum lycopersicum L.) production, as it stimulates root growth by improving water use efficiency and nutrient uptake. It also helps control the metabolic processes of ATP (energy), sugars, and nucleic acids. Therefore, it is imperative to effectively manage the phosphorus requirements of tomatoes to bolster their productivity. The objective of this study was to evaluate the effectiveness of three different soil P testing methods that are suitable for the soils of Kano State, Nigeria, and to develop a critical P-value for fertilizer recommendations for tomatoes. Accordingly, sixty topsoil samples were collected for soil available P testing according to the Bray II, Mehlich 3, and Olsen methods. Moreover, to establish the phosphorus critical value (Pc) for tomatoes, a field experiment was conducted with seven different rates of P using triple super phosphate fertilizer (TSP), viz., 0, 15, 30, 45, 60, 75, and 90 kg P/ha, laid out in a randomized complete block design with three replications on 15 experimental sites representing the various agroecological zones of the state. Phosphorus fertilizer was applied and incorporated into the soil 1 week before tomato transplanting. Then, soil samples from 0 to 20 cm depth were taken 3 weeks after transplanting from all the plots across the experimental sites for separate Mehlich 3, Bray II, and Olsen extractable P analysis to determine the critical soil P (Pc) test. The study revealed that available P was varied and increased in the order of Olsen (2.19 ppm)< Mehlich 3 (5.37 ppm)< Bray II (5.44 ppm), and the Mehlich 3 and Bray II extraction methods were strongly correlated, whereas Olsen underestimated the available P, showing a weak correlation with both Mehlich 3 and Bray II. Furthermore, the study showed that phosphorus critical (Pc) values were 17.00, 14.00, and 4 ppm for Mehlich 3, Bray II, and Olsen respectively. Finally, Bray II was a more reliable method for estimating the available P on moderately acid soils as it showed the highest correlation r = 0.83 with the relative yield of the tomatoes and, therefore, was the most effective method for developing the equation for the soil test-based phosphatic fertilizer recommendation for maximizing tomato production in the soils of Kano State. Hence, the equation developed for the P fertilizer recommendation (Pr) for tomatoes in Kano State was found to be “Pr (kg P2O5 ha−1) = (14.0 − Pi) × 9.02”.

Effect of Phosphorous and Biochar Levels on Phosphorous Concentration in Plants and some Growth Characteristics and Yield of Wheat (Triticum aestivum L.)

A field experiment was carried out during the 2021-2022 agricultural season in Al Bandar area, which is located 10 km east of the center of Samawah city - Muthanna governorate on the left side of the Euphrates River to find out the effect of phosphorous and biochar levels on the growth characteristics and yield of bread wheat, triple superphosphate fertilizer TSP (21%) was used. as a source of phosphorous fertilizer with five levels (0, 50, 75, 100 and 150%) of the fertilizer recommendation (120 kg P ha−1) and biochar was used, as a volume of 120 cm3 was added to a box with three size levels (0%, 1% and 2%) It was added at once before planting, the experiment was carried out using a design (RCBD) with three replicates, The levels of phosphorous and biochar achieved the best values in all study parameters.

Impacts of U.S. countervailing duties on phosphate fertilizers

AbstractCountervailing duties are a trade policy instrument by which importing governments tax imports that are found to benefit from foreign subsidies. Thus, in effect, these duties attempt to remedy market distortions generated by foreign subsidies by further distorting market mechanisms. On March 11, 2021, the U.S. International Trade Commission issued duties ranging between 19.97% and 47.05% on Moroccan phosphate imports upon finding that Moroccan exports had been receiving unfair government subsidies. In this research, we estimate the impacts of these duties on U.S. diammonium phosphate and triple superphosphate fertilizers, as well as long‐run downstream prices of five U.S. row crops with the largest phosphate usage. Using these results, we assess the implications for gross receipts in the U.S. fertilizer industry and gross margins for American farmers. We also calculate the implied change in expenditure for agricultural end users. We find that the countervailing duties have increased U.S. phosphate fertilizer prices by approximately 34% over counterfactual levels. This corresponds to an expected downstream price response ranging from around 10% for corn, cotton, and sorghum to between 1% and 4% for soybeans and wheat. This market distortion generates a $23 billion increase in gross receipts for a concentrated domestic fertilizer industry while shrinking gross margins for American farmers by 2% and 8% and increasing agricultural user expenditures by approximately $10.84 billion.

Crop nutrition and grain yield as affected by phosphorus fertilization and continued use of phosphogypsum in an Oxisol under no-till management

ABSTRACT The benefits of applying phosphogypsum to the soil are widely known. However, the effect of phosphogypsum on phosphate fertilization efficiency is still unclear. A long-term field experiment was performed on an Oxisol in Parana State, Brazil to evaluate the effects of triple superphosphate (TSP) and phosphogypsum application rates on nutrition and grain yield of soybean, wheat, and black oat under no-till. Applying TSP in the sowing furrow of soybean and wheat increased soybean yield by 14 to 24%, wheat yield by 57%, and black oat yield by 78%. Soybean yields varied in different cropping seasons in response to phosphogypsum application (with no response to increases of up to 15% in yield), while phosphogypsum increased wheat yield by 23% and black oat yield by 59%. The water balance during crop flowering possibly interfered on crop yield response to phosphogypsum. The use of phosphogypsum increased agronomic P-use efficiency by 20%, regardless of the TSP-P application rates. Changes in P-leaf concentration caused by TSP fertilization and phosphogypsum use had a positive impact on crop grain yield. Our results reveal that the continued use of phosphogypsum to alleviate subsoil acidity could increase the phosphate fertilization efficiency and improve crop yield performance under drought stress.

Evaluation of phosphorus runoff from sandy soils under conservation tillage with surface broadcasted recovered phosphates

Potential new sources of phosphorus (P) fertilizer are the recovered P from livestock wastewater through chemical precipitation and the ash from combusting animal manures. Although most of the research on P losses from conservation tillage include high water-soluble P compounds from commercial fertilizer sources, information on the use of non-conventional, low water-soluble, recycled P sources is scarce. Particularly for sandy soils of the United States (US) Southeastern Coastal Plain region, research driven information on P loss into the environment is needed to determine recommendations for a direct use of new recycled P sources as crop P fertilizers. The objective of this study is to investigate the potential P runoff from sandy soils under conservation tillage, fertilized with recovered P from liquid swine manure and turkey litter ash in comparison with commercial P fertilizer triple superphosphate (TSP). The field study included two typical sandy soils of the US Southeastern Coastal Plain region, the Noboco and Norfolk. Simulated rain corresponding to the annual 30-min rainfall in the study site (Florence County, South Carolina) was applied to plots treated with recovered P from liquid swine manure, turkey litter ash, and TSP, including a control with no P added. The runoff was monitored and sampled every 5 min during the test and composite soil samples were collected from the top (0–15 cm) and subsurface (15–30 cm) soil layers in each plot. Laboratory analyses were conducted to quantify both total P (TP) and soluble reactive P (SRP) in runoff samples, and the soil test P in the soil layers. Two-way analyses of variances show significant treatment effects on both TP and SRP runoff. The quantities of SRP runoff from plots treated with the recovered P from swine manure and turkey litter ash represent respectively 1% and 7–8% of SRP runoff from plots treated with TSP. Hence, the use of the recovered P materials as crop P fertilizers through surface broadcast application present less environmental risks compared to commercial TSP.

Experimental dissolution of biopolymer-coated phosphorus fertilizers applied to a soil surface: Impact on soil pH and P dynamics

Biopolymer-coated phosphorus fertilizers have shown promising results in slowing the release of P. However, their dissolution behaviour has been studied mainly in water, and their impacts on soil properties have rarely been addressed. The aim of this study was to compare the dissolution of P from uncoated triple superphosphate (TSP) and biopolymer-coated TSP fertilizers at the surface of cropped Mediterranean soils and to evaluate their impacts on the soil pH and the distributions of several P pools. The experimental treatments were: no fertilizer, uncoated TSP, TSP coated with lignin and TSP coated with lignin and carrageenan. The spatial and temporal variations in the pH of the fertilized soils were investigated using optodes. The concentrations of different pools of P (available P, microbial P), and total P as well as P recovery at different distances from the granules were determined. The coated TSP acidified the soil to a radius of 14 mm around each fertilizer granule, while the acidification spread to 21 mm in the treatment with the uncoated TSP. Moreover, an increase in microbial P was observed in the soil treated with coated TSP, possibly due to the carbon input and the consequent increase in microbial biomass. However, slower P-release was observed from the coated TSP due to the effect of the coating barrier. The P recovery results showed P migration within a 21 mm radius from each granule, and the P recovery from the TSP coated with lignin alone was significantly greater than that from the uncoated TSP treatment.

Preferences of Pinus sylvestris seedling roots for different phosphorus sources under phosphorus-deficient conditions

PurposePhosphorus (P) is a limiting nutrient in many managed forests. To further understand the risks and benefits of biochars as sustainable P source in forest management, an improved mechanistic understanding of its interactions in root systems is required.MethodsA rhizobox experiment was conducted to observe root response of P. sylvestris (Scots pine) seedlings to different biochars in comparison to triple superphosphate (TSP) fertiliser as a P source. Three types of wood-derived biochar were compared: biochar from mixed softwood pellets (“Reference biochar”); from the vascular cambium zone of Picea sitchensis (“VCZ biochar”) and from mixed softwood pellets infused with TSP (“Processed biochar”). These biochars presented a range of available P from low to high. Seedling root development was spatially analysed using GIS software.ResultsThe total length of P. sylvestris roots did not significantly differ between treatments. However, seedling roots showed strong preference for soil proximal to VCZ biochar and strong avoidance to TSP fertiliser. There was a milder avoidance effect for Processed biochar. Differences in root responses could be explained by available P: roots favored a moderate, sustained P source and avoided high available P sources. The avoidance effect can be attributed partially to lower soil pH around TSP fertiliser.ConclusionThe extent concentration and duration of P availability affects the root response of P. sylverstris to P sources. Under P-deficient conditions, P. sylvestris root growth was markedly improved by introducing biochar with a certain P concentration, and VCZ biochar has potential as an effective source of P in forest establishment.

Improving Tropical Soil Productivity and Cowpea (Vigna unguiculata (L.) Walp) Performance Using Biochar and Phosphorus Fertilizer

ABSTRACT Studies on the effects of biochar and phosphorus fertilizer on soil productivity and yield of cowpea (Vigna unguiculata) are scarce. Therefore, experiments were conducted in 2019 and 2020 to evaluate the effects of sole and combined application of biochar and phosphorus fertilizer on soil properties, nodulation, growth, and yield of cowpea. The treatments consisted of: biochar at 10 t ha−1 (B10), biochar at 20 t ha−1 (B20), triple super phosphate fertilizer at 60 kg P ha−1 (P), biochar at 10 t ha−1 + P (B10 + P), biochar at 20 t ha−1 + P (B20 + P), and the control. The experimental design was a randomized complete block design with three replications. Results revealed that biochar and P fertilizer applied alone or in combination improved soil properties, growth, nodulation, and yield of cowpea compared with the control. Results also showed that combined applications of biochar with P fertilizer improved these properties most, especially at a higher rate of biochar (B20 + P). B20 + P increased grain yield of cowpea by 155%, 69%, 53%, 69%, and 21% respectively compared with the control, B10, B20, P fertilizer, and B10 + P. This was adduced to raise soil pH and reduced soil bulk density as a result of biochar application which induces P solubility and availability, increased N fixation, and enhanced root growth, increased nodulation leading to improved growth and yield of cowpea. Application of biochar with P fertilizer could therefore be used as a strategy for improving P availability in low pH soils of cowpea growing areas of the tropics.

Recycling-derived Phosphorus Fertilizers as a Sustainable Alternative to Triple Superphosphate Fertilizers

Microbial activity is adamant for the nutrient cycling in soil. Generally, mineral phosphorus (P) fertilizer is applied to soil to improve plant growth, however, significant amounts are immobilized quickly. Mineral fertilizer can cause soil degradation, affecting the microbial community. Alternative, recycling-derived fertilizers (RDFs) need to be evaluated as suitable replacement for finite mineral P fertilizer. The impact of four RDFs (two ashes, two struvites) on the soil microbiome in comparison with a P-free control and triple superphosphate (TSP) as mineral fertilizer was investigated in a pot trial and a subsequent microcosm trial (subset of samples). For both experiments, perennial ryegrass was cultivated for 54 days. The pot trial was conducted at P fertilization rates of 20 and 60 kg P ha-1 in quadruplicates. After the pot harvest, the bulk soil was stored until the microcosm trial was conducted, using the control, TSP and the two ashes at 60 kg P ha-1 in six replicates. Struvites displayed highest P bioavailability at high P application rates in the pot trial, yielding higher biomass on average. Furthermore, P solubilization from tri-calcium phosphate was enhanced in the RDFs treatments, while the TSP treatments were negatively affected. For the microcosm trial, most probable number (MPN) analysis showed that phytate-utilizing bacterial abundance was significantly increased in one of the ashes. Non-metric multidimensional scaling (NMDS) analysis of phoD illumina sequencing data showed significant separation between all treatments of the microcosm trial. Understanding the impact of RDF application on the soil P cycle is vital to sustainable agriculture.

Biology and life table parameters of Callosobruchus maculatus (F.) on Vigna unguiculata (L.) Walp. fertilized with some mineral- and bio-fertilizers

Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae), a major pest of stored cowpea Vigna unguiculata (L.) Walp., causes critical losses by decreasing the grain weight, germination ability and nutritional quality. Improving host plant resistance by the application of appropriate fertilizers would be effective in reducing C. maculatus infestation. The effects of some mineral- (triple superphosphate (TSP) and urea) and bio-fertilizers (Bradyrhizobium japonicum, Pseudomonas putida, mycorrhizal fungi, and a mixture of them) were evaluated on the susceptibility of stored cowpea grains to C. maculatus. Cowpeas fertilized with examined fertilizers were cultivated at farm conditions. Then, the mature, dry grains were harvested and used to investigate the pest's life cycle and life table characteristics under 28 ± 1 °C, 65 ± 5% R.H., and total darkness. Developmental time of C. maculatus on TSP-treated grains was shorter than on control and P. putida treated ones. However, the lowest immature survival and fecundity (number of deposited eggs) was on TSP-fertilized grains. The intrinsic rate of increase (r) and net reproductive rate (R0) were the lowest on the grains treated with TSP. The highest tannins and starch content in the grains fertilized with TSP may be the critical reasons for their resistance to C. maculatus in storage. Application of TSP fertilizer can be recommended to increase cowpea resistance to this pest.

Phosphate fertilization affects rhizosphere microbiome of maize and sorghum genotypes.

Despite the lower reactivity of natural phosphates compared to soluble fertilizers, their P bioavailability can increase over the cultivation years, due to the physicochemical processes and the activity of soil microbiota. Therefore, this work aimed to evaluate the α and β diversity of the rhizosphere microbiota of maize and sorghum genotypes grown under different sources and doses of phosphate fertilizers. Four commercial maize and four sorghum genotypes were grown under field conditions with three levels of triple superphosphate (TSP) and two types of rock phosphate sources: phosphorite (RockP) and bayóvar (RP) during two seasons. Maize and sorghum presented a significant difference on the genetic β diversity of both rhizosferic bacterial and arbuscular mycorrhizal fungi. Moreover, P doses within each phosphate source formed two distinct groups for maize and sorghum, and six bacterial phyla were identified in both crops with significant difference in the relative abundance of Firmicutes and Proteobacteria. It was observed that RockP fertilization increased Firmicutes population while Proteobacteria was the most abundant phylum after TSP fertilization in maize. In sorghum, a significant impact of fertilization was observed on the Acidobacteria and Proteobacteria phyla. TSP fertilization increased the Acidobacteria population compared to no fertilized (P0) and RockP while Proteobacteria abundance in RockP was reduced compared to P0 and TSP, indicating a shift toward a more copiotrophic community. Our results suggested that the reactivity of P source is the predominant factor in bacterial community' structures in the maize and sorghum rhizosphere from the evaluated genotypes, followed by P source.

Uptake of Phosphorus from Modified P-Enriched Douglas Fir Biochar and Its Effects on Crop Growth and P Use Efficiency

The potential use of biochar as a sustainable soil amendment has recently gained global recognition. The use of biochar as a soil additive is attributed to its ability to improve soil chemical, physical and biological properties. Studies have shown that biochar amendments can enhance soil nutrient retention and availability, pH, water holding capacity, microbial activity and sequester carbon. In this study using corn (Zea mays L.) as an experimental crop, the influence of P availability from modified P enriched Douglas fir biochar (PEB), triple super phosphate fertilizer (SPF), and modified Douglas fir biochar (MB) on plant growth and P Use Efficiency (PUE) were compared. The rate of P applied (0, 30, 60, 90 and 120 kg·ha-1) was calculated based on % P content of each soil additive. Except for MB treatments, P recovery, crop growth and P Use Efficiency increased with application rates. The maximum above ground dry matter yields corresponding to PEB, SPF and MB treatments were estimated at 3488 kg·ha-1, 2449 kg·ha-1 and 639 kg·ha-1, while their respective agronomic P use efficiency (AGE) rates were 32 kg·kg-1, 17 kg·kg-1, 0.5 kg·kg-1. Also, recovery of K, Mg, Ca, Zn, Fe, Cu, B and Mn improved in both PEB (p value 2 > 0.9) and SPF (p value 2 > 0.9) treatments. More studies at field scale are needed to demonstrate the practicability of using modified P enriched Douglas fir biochar for soil amendments.

Effect of Various Rates of P from Alternative and Traditional Sources on Butterhead Lettuce (Lactuca sativa L.) Grown on Peat Substrate

Previous research indicated the potential use of struvite (STR) as an alternative source of phosphorus (P) in crop production. A greenhouse experiment was conducted to evaluate the effect of STR and triple superphosphate (TSP) on the growth and chemical composition of butterhead lettuce grown on peat substrate over a three-month period (May–July). Both alternative (STR) and conventional (TSP) fertilizers were applied at three rates: (1) recommended rate based on the elemental content of substrate and crop nutritional need; (2) reduced rate (50% lower than recommended); and (3) increased rate (50% higher than recommended). Unfertilized (control) plants were also grown in the pot experiment. As expected, fertilizer application tended to increase the content of heavy metals in the substrate. Thus, an increase in Zn, Pb, and Cu content in peat substrate was found following STR amendments. However, compared with unfertilized plants, the applied rates of the STR and TSP fertilizers did not increase the content of Cd and Cu in the plant leaf, while Hg content was below the detection limit. In addition, Zn content in the plant leaf significantly decreased following STR and TSP applications. In comparison to unfertilized plants, both alternative and conventional fertilizers increased the content of P and nitrate nitrogen (N-NO3−) in the plant leaf while their effect on Mg content was negligible. The increased rate of STR was the best fertilizer treatment because it produced the largest number of leaves, which were also characterized by the highest P content. Our findings showed that STR was an effective source of P in butterhead lettuce cultivation without adverse effects on heavy metal accumulation.