Inorganic Phosphorus Fertilizers Research Articles

Effect of Different Levels of Phosphorus, Phosphorus Solubilising Bacteria and Farmyard Manure on Nutrient Content and Uptake by Bt-Cotton

Aim: To determine the effect of integrated use of inorganic phosphorus along with phosphorus solubilising bacteria and farmyard manure on nutrient Content and uptake in Bt-Cotton.
 Study Design: The experiment was laid out in randomized block design with three replications.
 Place of Study: At College Farm, Agricultural College, Bapatla, Guntur district.
 Methodology: After the preliminary layout, the Tulasi-BG II hybrid of cotton was used as a test crop, with a spacing of 90 cm x 60 cm in the experimental site. Plant samples were collected at 45, 90 DAS, and harvest. Plant samples were shade dried and kept in hot air oven at 75°C until a constant weight was obtained. Samples were powdered and then analysed using standard chemical procedures.
 Results: The uptake of macronutrients viz., N, P, and K was markedly influenced by the treatments with maximum values recorded by the treatment that received 60 kg P2O5 ha-1 + FYM + PSB. Their uptake significantly differed with increase in dose of phosphorus applied at all growth stages. Combined use of 60 kg P2O5 ha-1 + FYM + PSB resulted in a significant increase in uptake of all micronutrients (Zn, Cu, Mn, and Fe) at all stages except Cu at 90 DAS.
 Conclusion: Application of phosphorus combined with FYM and PSB not only reduce inorganic phosphorus fertilization but also enhance the uptake of nutrients and plant nutrient content by providing favourable conditions for plant growth. Application of 30 kg P2O5 ha-1+ PSB + FYM was found to be on a par with addition of only 60 kg ha-1P2O5. Hence the P dose can be reduced to half by integrating with PSB and FYM.

Effectiveness of plant growth promoting microrganisms as biofertilizer for soybeans under oil palm plantations on tidal land

A research to study the effectiveness of biofertilizers on nodulation, growth and productivity of soybean was carried out at two locations on type D tidal lands in South Kalimantan, using a randomized block design with four replications. The treatments tested were N-fixing bacteria Rhizobium japonicum, P solubilizing bacteria (PSB) Pseudomonas sp and mycorrhiza biofertilizers, combined with inorganic nitrogen (N) and phosphorus (P) fertilizers in the form of Urea and SP36 with low (25:25), moderate (50:50) and high (100:100) kg/ha doses. At the first location, the highest seed yield (2.04 t ha) was obtained in the rhizobium + PSB treatment combined with moderate dose of Urea and SP36 (50:50). This yield was 34% increase compared to seed yield at the same fertilizer rate without any biofertilizer. The same response was also obtained in second location where the soil was more acidic. The highest seed yield (1.9 t/ha) was obtained in the rhizobium + PSB treatment with a moderate dose of N and P fertilizer (50:50). This treatment resulted in 70% yield increase compared to that obtained by the treatment of the same fertilizer rate without bio fertilizer. In treatment of rhizobium + PSB + mycorrhiza, the seeds yield obtained were not different from the rhizobium + PSB treatment. This yield increase was supported by increasing the number and weight of root nodules, leaf chlorophyll index, weight of 100 seeds, and the number of filled pods per plant. This shows that the tested biofertilizers was effective on tidal land, and was able to increase soybean productivity.

Effects of long-term organic amendment on the fertility of soil, nodulation, yield, and seed quality of soybean in a soybean-wheat rotation system

Organic amendment has long been recognized as an effective approach to improve soil fertility and plant nutrition. Most studies on long-term organic amendment in fields have focused on cereals. The effects of long-term organic amendment on legumes remain largely unknown. Here we studied the impact of organic amendments, including straw and manure on the soil fertility, nodulation, seed yield, and seed quality in a 27-year experiment. The long-term fertilizer treatments were laid out using a randomized complete block design designed with three replications in the first year of experimentation (1990). Fertilization treatments were CK (no fertilization), NPK (inorganic nitrogen, phosphorus and potassium fertilizers), NPKS (Straw together with inorganic N, P, and K fertilizers), and NPKM (manure together with inorganic N, P, and K fertilizers). The layout was subsequently maintained in the following years to clearly understand the effect of long-term application of each treatment. Maize (Zea mays L.)-wheat (Triticum aestivum L.) rotation was the main long-term experiment cropping system from 1990 to 2011; from 2012 it becomes wheat-soybean (Glycine max L.) rotation. We found that NPKS, NPKM, and NPK increased organic matter by 34.7%, 36.24%, and 17.17%, respectively, and total nitrogen by 28.9%, 29.7%, and 25.2%, respectively, in comparison with CK. Organic amendment also increased enzymatic activity of phenol oxidases and β-1,4-glucosidases. The NPKS and NPKM increased soybean yields by 30.8% and 29.6%, respectively, in comparison with NPK alone and CK. The soybean yields significantly correlated with NO3-N, available phosphorus, available potassium and soil organic matter. Both the inorganic fertilizers and organic amendments did not significantly alter soybean nodule number and size. NPKS and NPKM applications significantly reduced fat content by 1.17% and 1.26%, respectively, as opposed to NPK fertilized treatments alone (0.34%), compared with those under CK, but did not affect soybean protein. Overall, the combination of straw returning with inorganic fertilizers and manure with inorganic fertilizers improves soil fertility and increases soybean productivity. However, organic amendments together with inorganic fertilizers might have an undesirable effect on soybean fat content. Organic amendments combined with NPK application have the highest value of protein content and increased nitrogen to the soil. High nitrogen reduced fat and increased protein content. Therefore, rate of N inputs should be adjusted under the application of organic amendments together with inorganic fertilizers in fluvo-aquic soil.

Analisis Ketersediaan Kadmium di Tanah dan Beras Yang Berasal dari Desa Detusoko Barat

Cadmium is a heavy metal that is widely found in agricultural land because of the frequent use of inorganic phosphorus fertilizers. The use of high phosphorus inorganic fertilizers is also used by farmers who cultivate rice in Detusoko Barat Village. Therefore, research has been carried out with the aim of knowing the cadmium content in paddy soil and rice and its comparison with the minimum limit of cadmium in rice and soil. This research is survey research, in which the determination of soil and rice samples using a purposive sampling method. From this method, the soil samples taken are rice fields cultivating Palembang, Bengawan and Kental rice varieties. And the rice samples taken were rice from the three varieties. The variables observed were cadmium from the soil and rice and soil pH. The results showed that the cadmium content in Palembang rice soil was 0.015 ppm, Bengawan 0.006 ppm, and thick 0.001 ppm, while the results of the research on cadmium content in Palembang rice were 0.007 ppm, Bengawan rice was 0.008 ppm, and thick rice was 0.006 ppm. Where the cadmium content in rice is still below the minimum limit that has been set.

Integrated Nutrient Management Enhances Soil Quality and Crop Productivity in Maize-Based Cropping System

Soil quality deterioration, especially in intensive cropping systems, has become a serious problem for crop productivity; consequently, strategies for sustainable crop production and soil health are urgently required. Experiments on fields were organized to investigate the impact of organic manures on crop productivity, soil physiochemical properties and soil water availability in a maize-based cropping system. The experiment consisted of five treatments, including organic manures (OM) and inorganic nitrogen, phosphorus and potassium (NPK) fertilizers applied separately and in combinations: NPK = 250-150-125 Kg/ha (recommended rate), farmyard manure (FYM) = 16 t/ha, poultry manure (PM) = 13 t/ha, NPK + FYM = 150-85-50 Kg/ha + 8.5 t/ha and NPK + PM = 150-85-50 Kg/ha + 7.0 t/ha. The results showed that the combination of OM with mineral fertilizers increased crop productivity, fertilizer use efficiency and yield sustainability indices over the treatments amended with sole application of mineral fertilizers and OM. The analysis of undisturbed soil samples during different crop growth stages revealed that the addition of OM decreased the bulk density and increased the pore volume of soil at the beds of 0–20 and 20–40 cm. The application of OM to the soil not only increased saturated hydraulic conductivity of the soil but also improved total available and readily available water contents to the plants, especially when FYM was included at 16 t ha−1. Soil-water retention properties recorded over the entire seven-day monitoring period following irrigation in the OM-amended treatments were consistently higher than the sole mineral NPK application treatments. When testing the soil nutrient status during different crop growth stages, it was noted that by adding OM into the soil not only the status of the organic carbon of soil, extractable N and K and available P contents is increased, but the duration of their availability to the plants are also enhanced. The results of the study show that organic manures addition is of major significance for maintaining soil quality and crop production sustainably, and should be advocated in the nutrient management strategies of intensive water- and nutrient-demanding cropping systems.

Application of biochar and inorganic phosphorus fertilizer influenced rhizosphere soil characteristics, nodule formation and phytoconstituents of cowpea grown on tropical soil

The effect of biochar alone or co-applied with triple superphosphate on rhizosphere soil characteristics, nodule formation, phytoconstituents and antioxidant property of cowpea (Vigna uguiculata) is yet to be adequately examined in sub Saharan Africa. A field experiment was conducted where cowpea (Vigna unguiculata) was grown in a tropical sandy loam soil amended with biochar at 1.5 t ha−1 and 2.5 t ha−1 solely or together with inorganic phosphate fertilizer (Triple superphosphate), applied at a rate of 60 kg P ha −1. At 50% flowering, changes in selected rhizosphere soil properties (pH, total nitrogen, available phosphorus, soil organic carbon, cation exchange capacity), nodule count, phytochemicals (phenols, flavonoids, alkaloids, tannins, saponins) and antioxidant property of cowpea roots and leaves were determined by standard laboratory procedures. Differences between means of the measured parameters were established using ANOVA, and relationships among the parameters were explored using Pearson correlation (p < 0.05). Addition of biochar solely or in combination with TSP significantly (p < 0.05) increased soil pH, total nitrogen, available phosphorus, soil organic carbon, cation exchange capacity and root nodule count. Flavonoids, phenols, alkaloids, saponin, tannin contents and antioxidant activity in the roots and leaves were significantly (p < 0.05) higher in the amended soils compared with the unamended soil. Similarly, soil flavonoids, phenols, alkaloids and antioxidant activity were significantly higher in amended soils compared with control. Significant, positive inter and intra correlation with varying strength was found between soil properties, nodule number and phytoconstituents. This is an indication that biochar can be co-applied with triple superphosphate to sustain soil fertility, improve nodulation and enhance concentrations of phytoconstituents in soil, cowpea roots and leaves.

Effect of organic and inorganic phosphorus fertilizers on phosphorus availability and its leaching over incubation time.

The use of organic and inorganic phosphorus (P)fertilizers in agricultural soils is very common, and few studies have been conducted to study the effect of different P sources on relative P extractability (RPE) and leaching using different P extractants and degree of P saturation (DPS), over a long period of time. Thus, this study was conducted to investigate the effect of incubation time and different P sources on RPE, DPS, and to predict the concentration of P leached from soil using different P extractants. In order to achieve these goals, nine sewage sludges (SSs), two biochars, animal manure (AM), poultry manure (PM), wheat residue (WR), diammonium phosphate (DAP), and triple superphosphate (TSP) were added to the soil as much as 100mg P kg-1 in a 163days incubation experiment. On average across all amendments and incubation periods, Mehlich-3 extractable P (M3EP) gave the highest mean RPE (42.9%, SE = 7.1%), with water-extractable P (WEP) the lowest (4.6%, SE = 0.93%), and Olsen-extractable P (OEP) (38.3%, SE = 6.3%) in between. Among SSs and based on average across of all incubation periods, soils treated with Shiraz and Takestan SSs were the least soluble source of P, while the highest soluble source of P were soils treated with Kermanshah and Tehran SSs. The results indicated that soil samples taken 16days following the addition of amendments should reflect agronomic and environmental purposes aiming to assess available and the potential P loss from agricultural soils. The split line model perfectly fitted to the relation between OEP and M3EP (r = 0.93). The DPSs were calculated and the P leaching rate was estimated. Based on OEP, the soils treated with TSP and DAP were at high risk, the medium risk was for soils treated with Kermanshah, Saveh, Tehran, Rasht, Sanandaj, and Isfahan SSs, and PM. Control soil, and soils treated with WRwere at no risk, and the soils treated with Arak, Shiraz, and Takestan SSs, ABC, WBC, and AM were classified as low risk.

An Assessment of Climate Induced Increase in Soil Water Availability for Soil Bacterial Communities Exposed to Long-Term Differential Phosphorus Fertilization.

The fate of future food productivity depends primarily upon the health of soil used for cultivation. For Atlantic Europe, increased precipitation is predicted during both winter and summer months. Interactions between climate change and the fertilization of land used for agriculture are therefore vital to understand. This is particularly relevant for inorganic phosphorus (P) fertilization, which already suffers from resource and sustainability issues. The soil microbiota are a key indicator of soil health and their functioning is critical to plant productivity, playing an important role in nutrient acquisition, particularly when plant available nutrients are limited. A multifactorial, mesocosm study was established to assess the effects of increased soil water availability and inorganic P fertilization, on spring wheat biomass, soil enzymatic activity (dehydrogenase and acid phosphomonoesterase) and soil bacterial community assemblages. Our results highlight the significance of the spring wheat rhizosphere in shaping soil bacterial community assemblages and specific taxa under a moderate soil water content (60%), which was diminished under a higher level of soil water availability (80%). In addition, an interaction between soil water availability and plant presence overrode a long-term bacterial sensitivity to inorganic P fertilization. Together this may have implications for developing sustainable P mobilization through the use of the soil microbiota in future. Spring wheat biomass grown under the higher soil water regime (80%) was reduced compared to the constant water regime (60%) and a reduction in yield could be exacerbated in the future when grown in cultivated soil that have been fertilized with inorganic P. The potential feedback mechanisms for this need now need exploration to understand how future management of crop productivity may be impacted.

Soil nutrients and heavy metal availability under long-term combined application of swine manure and synthetic fertilizers in acidic paddy soil

Fertilization is a vital approach to increase the crop yield by enhancing soil fertility, but some of the fertilizer sources such as pig manure contain non-essential toxic heavy metals, which can produce the environmental and public health risk. Therefore, the purpose of this study was to investigate the soil fertility and heavy metal pollution risk under long-term fertilization in acidic paddy soil. Fertilizer treatments that were arranged in randomized complete block design (RCBD) included CK (no fertilization), NK (inorganic nitrogen and potassium fertilization), NPK (inorganic NK and phosphorus fertilization), NPKM1 (70% of NPK and 30% pig manure application), NPKM2 (50% of NPK and 50% of pig manure application), and NPKM3 (30% of NPK and 70% of pig manure application). The rice grain yield and soil nutrient contents were highest under NPKM3 treatment. Long-term addition of manure significantly (P ≤ 0.05) increased soil pH and SOC content compared to the NPK fertilization. Soil available and total Cr, Cd, and Hg contents were highest under NPKM3 treatments, while soil total and available Pb content was significantly (P ≤ 0.05) higher under NPK treatment. Highest ecological risk (IR) was (1904) under NPK treatment and highest pollution load index (PLI) was 1.5 under NPKM3 treatment. Cd concentration in rice grain exceeded the maximum permissible limit of 0.1 mg kg−1 under combined application of manure and inorganic fertilization treatments. Grain Cr, Hg, and Pb contents were within safe limits of their concentration in all treatments. Moreover, biological accumulation coefficients of Cr, Cd, Hg, Pb, Zn, and Cu were highest under NPK treatment. Redundancy analysis (RDA) showed that soil pH and nutrient contents showed significant correlation with heavy metal concentrations in soil. Soil pH showed significant (P ≤ 0.05) positive effect on Cd accumulation in rice grain. Heavy metals in pig manure should be monitored before application to the field to reduce the risk of heavy metal pollution in soil and plant. Furthermore, combined application at the rate of 70% inorganic fertilization and 30% of manure could be better strategy to produce high crop yield with minimum risk of heavy metal contamination in soil and food crops.

Cover Cropping May Alter Legacy Phosphorus Dynamics Under Long-Term Fertilizer Addition

Use of cover crops in an integrated agricultural system can reduce demand of inorganic phosphorus (P) fertilizers, where the subsequent crops can take up P accumulated in cover crops biomass after the decomposition. In this research we hypothesized that some cover crops can take up P from less labile fractions and recycle it back to the soil through plant residues resulting in better P use efficiency of the system; cover crops are capable of P uptake from subsurface layers which leads to the accumulation of this P on the surface after the decomposition of their residues; and cover crop species respond differently to distinct inorganic P sources. To examine these hypotheses, a field experiment was conducted over nine successive years in South Brazil. The experimental treatments were established as a split-plot randomized block design, in a 3 × 6 factorial scheme, considering three P treatments [no-P, single superphosphate (SSP), and rock phosphate (RP)] as main plot and six cover crop treatments (common vetch, white lupin, fodder radish, ryegrass, black oat, and a fallow) as subplots. Soil samples were collected from the depths of 0–5, 5–10, and 10–15 cm and analyzed by Hedley P fractionation. In P-unfertilized cropping system, the amounts of labile and mod-labile P fractions were not modified by cover crops related to fallow. When inorganic P fertilizers were applied, the amount of labile and mod-labile P pools under fallow were higher than under cover crops in 5–10 cm depth. Black oat and common vetch cycled more labile P under SSP and RP, respectively. Common vetch and ryegrass resulted in the highest accumulation of organic P on the surface under SSP and RP, respectively. Black oat was capable to change P extracted by 1.0 M HCl to more labile forms. Fodder radish showed the highest P uptake in comparison with other cover crops. The higher P balance efficiency of the system was achieved under SSP in comparison with RP application but it seems that cover crops are more effective at improving the efficiency under RP compared to SSP.

Assessing modified aluminum-based water treatment residuals as a plant-available phosphorus source

Inorganic phosphorus (P) fertilizers are a finite resource; alternative means of creating P fertilizers from current municipal and agricultural waste sources may reduce our reliance on phosphate rock mining, and improve waste disposal and nutrient cycling. Previous research demonstrated that organic aluminum water treatment residual composites (Al/O-WTR), created by mixing aluminum water treatment residuals (Al-WTR) with swine wastewater, have the potential to be a source of plant-available P. A greenhouse study was conducted to compare spring wheat (Triticum aestivum L.) growth with increasing application rates of swine wastewater-derived Al/O-WTR and commercial P fertilizer (both applied at 34, 67, and 135 kg P2O5 ha−1) in either sandy loam or sandy clay loam soil. Spring wheat straw and grain P uptake were comparable across all treatments in the sandy loam, while straw and grain P uptake were lower with Al/O-WTR in the sandy clay loam. The Al/O-WTR did not affect soil organic P concentrations, but did increase phosphatase activity in both soils. Increased phosphatase activity suggests that Al/O-WTR application stimulated microorganisms and enhanced the extent to which microbial communities mineralized Al/O-WTR-bound organic P. Overall, these results suggest that Al-WTR can be used to make P fertilizer, combining two “waste” products to create a useful product. Phosphorus harvesting via Al/O-WTR may be a feasible future alternative to mining phosphate rock, while avoiding unnecessary waste disposal and improving agricultural nutrient cycling.

Response of Head Cabbage (&amp;lt;i&amp;gt;Brassica olearacea L.&amp;lt;/i&amp;gt;) Yield to Application of Different Rates of Inorganic Nitrogen and Phosphorus Fertilizers at Bore, Southern Ethiopia

The field trial was conducted during 2017 and 2018 main cropping season at the Bore Agricultural Research Centre which is located in Gudji Zones, of Southern Ethiopia to determine the effect of different application rates of nitrogen and phosphorus fertilizers on growth, yield and yield components of head cabbage and to identify their economically appropriate rates that maximize yield of head cabbage. The experiment was carried out to study cabbage variety Olsen to added N and P nutrients in respect to growth, yield and yield related parameters of the crop. The longest head initiation (90 days) and longest (140) days to maturity was attained in 294 kg ha^-1 Nitrogen and 138 kg ha^-1 phosphorus treatment, while shortest head initiation (64.33 days) was obtained in control treatment. The maximum plant height (26.4 cm) was recorded for the treatment T3P4 (235 +138 kag ha^-1), while the lowest (16.9 cm) plant height was recorded from the T1P1 (control) treatment. Nutrient levels markedly influenced the diameter, height, head mass and yield of head cabbage. The maximum average head diameter (25.44 cm) and average height (27.33 cm) was recorded in treatment receiving 235 kg N and 82 kg P ha^-1. Combined application of 235 kg N ha^-1 with the 82 kg P ha^-1 produced the highest (2356.67 g) untrimmed head weight of cabbage followed by second maximum (2133.33 g) untrimmed head weight with the rate of 235 kg N ha^-1 with the 110 kg P ha^-1 while the least (1120.67 g) untrimmed head weight was recorded for the control treatment. Combined application of 235 kg nitrogen and 82 kg phosphorus ha^-1 (N3P2) recorded maximum (69.00 t) head yield without wrapper ha^-1 and the lowest (27.66 t ha^-1) was recorded by control treatment. The marginal rate of returns, which determines the acceptability of any treatments shows that treatments that received 235 kg N ha^-1 in combination with 82 kg ha^-1 of P yielded 43498% marginal revenue. Therefore, this combined nutrient application rates can be recommended in the research area and similar agro-ecologies since it is the most feasible rates for the producers because of its low cost of production and higher benefits.

Yield sustainability, soil organic carbon sequestration and nutrients balance under long-term combined application of manure and inorganic fertilizers in acidic paddy soil

Organic and inorganic fertilization management in intensive cropping system is important to achieve long-term high crop yield sustainability. We quantitatively investigated crop yield sustainability through soil fertility and nutrients balance in 34-years long-term experiment under double rice cropping system in acidic paddy soil. Seven treatments were studied: CK (no fertilization); NPK (Chemical nitrogen, phosphorus and potassium fertilizer); NPM (Chemical N, P and manure); NKM (Chemical N, K and manure); PKM (Chemical P, K and manure); NPKM (Chemical N, P, K and manure) and M (Manure). Manure was applied at the rate of 45,000 kg ha−1. Results showed that crop yield and sustainability yield index under combined application of manure and chemical fertilizers was significantly higher than chemical fertilization and highest crop yield was under NPKM treatment. Long-term combined manure and chemical fertilization improved soil fertility as compared to CK and NPK treatments. Soil organic C sequestration rates under NPM, NKM, PKM and NPKM treatments were increased, while decreased under CK and NPK over the fertilization years. The uptake of N, P and K was increased over the fertilization years in all the treatments that received manure, compared with CK and NPK. Apparent K balance was negative in all the treatments. N balance (except CK and NPKM) and P balance (except CK) was positive in all fertilization treatments. P balance was exceeded the environmental risk threshold under combined application of chemical P fertilizer and manure. Boosted regression tree indicated that soil available N (AN), orgnaic carbon (OC) and total N (TN) were the most influencing factors of crop yield, accounted 36.5 %, 17.8 %, 13.4 % of variations of relative yield, respectively. Path analysis showed that long-term fertilizer inputs increased soil nutrient contents and C input directly affected soil OC. C input and soil pH indirectly influenced the relative crop yield. This study concluded that long-term combined application of manure and inorganic fertilizers increased crop yield sustainability, organic carbon sequestration rate compared to the inorganic fertilization. But long-term combined application of manure and inorganic phosphorus fertilizer increased the P balance. Therefore, rate of P inputs should be reduced under combined application of manure and inorganic P fertilizers in acidic paddy soil.

Influence of biodiversity and iron availability on soil peroxide: Implications for soil carbon stabilization and storage

AbstractIntensive agriculture results in soil degradation, especially with the depletion of soil organic carbon (SOC). Application of organic fertilizers (e.g., animal manures) alone or combined with chemical fertilizers can alleviate soil degradation by increasing soil C while causing variations in soil hydrogen peroxide (H2O2) and iron availability. However, the underlying relationships among soil H2O2 production, iron availability, and soil C storage following organic fertilization remain poorly understood. By combining results from three agroecosystem experiments from temperate northern to subtropical southern China with 25–29 years of different fertilization treatments (no fertilization, Control; inorganic nitrogen, phosphorus and potassium fertilization [NPK]; NPK plus manure [NPKM]), here, we show that NPK treatments increased soil H2O2 but decreased biodiversity (i.e., Shannon index) and SOC compared with NPKM treatments across all of the three experiments. In all of the examined soils, the contents of H2O2 were approximately 0.7– to 7–fold higher under NPK treatment than under Control or NPKM treatments. The contents of H2O2 were significantly affected by the fertilization regimes, experimental places, and their interaction. Compared with Control and NPKM treatments, NPK treatment decreased Shannon index to the greatest extent (~1.5) at the Qiyang experiment in subtropical southern China, followed by Jinxian (~0.6) in subtropical southern China, and Gongzhuling (~0.3) in temperate northern China. There was a significant and negative correlation between soil H2O2 and Shannon index or mobilized iron, indicating that high biodiversity and high mobilized iron were beneficial to the decay of soil H2O2. Results from microcosm experiments support the field observations, implying that the occurrence of microbial‐mediated Fenton‐like reactions or free radical reactions was influenced by organic inputs. Together, these findings suggest that long‐term manure inputs to soil initialize free radical reactions by activating microbial communities and mobilizing iron, providing benefits for soil C stabilization and storage by increasing recalcitrance and SOC interactions.

Phosphate acquisition efficiency in wheat is related to root:shoot ratio, strigolactone levels, and PHO2 regulation.

Inorganic phosphorus (Pi) fertilizers are expected to become scarce in the near future; so, breeding for improved Pi acquisition-related root traits would decrease the need for fertilizer application. This work aimed to decipher the physiological and molecular mechanisms underlying the differences between two commercial wheat cultivars (Crac and Tukan) with contrasting Pi acquisition efficiencies (PAE). For that, four independent experiments with different growth conditions were conducted. When grown under non-limiting Pi conditions, both cultivars performed similarly. Crac was less affected by Pi starvation than Tukan, presenting higher biomass production, and an enhanced root development, root:shoot ratio, and root efficiency for Pi uptake under this condition. Higher PAE in Crac correlated with enhanced expression of the Pi transporter genes TaPht1;2 and TaPht1;10. Crac also presented a faster and higher modulation of the IPS1-miR399-PHO2 pathway upon Pi starvation. Interestingly, Crac showed increased levels of strigolactones, suggesting a direct relationship between this phytohormone and plant P responses. Based on these findings, we propose that higher PAE of the cultivar Crac is associated with an improved P signalling through a fine-tuning modulation of PHO2 activity, which seems to be regulated by strigolactones. This knowledge will help to develop new strategies for improved plant performance under P stress conditions.

Soil carbon (C), nitrogen (N) and phosphorus (P) stoichiometry drives phosphorus lability in paddy soil under long-term fertilization: A fractionation and path analysis study.

Soil C:N:P stoichiometry plays a vital role in nutrient cycling in ecosystems, but its importance to P transformation in paddy soil remains unclear. We investigated the effect of soil C:N:P stoichiometry on P mobility and uptake under long-term fertilization. Three treatments, CK (no fertilization), NPK (inorganic nitrogen, phosphorus and potassium fertilization) and NPKM (combined inorganic NPK fertilizer and manure application), were selected from two long-term experiments of paddy soil that were initiated in 1991 and 1982 in Chongqing and Suining, respectively. The results showed that in comparison the control treatment, under long-term fertilization, soil pH decreased. In comparison with the NPK and CK treatments, the NPKM treatment significantly increased soil nutrient contents, P uptake and phosphatase activities. In comparison to the CK treatment, the NPK and NPKM treatments significantly decreased soil C:N, C:P and N:P ratios. In comparison to NPK and CK treatments, the NPKM treatment decreased residual-P at both sites. Compared with CK treatment, the NPKM treatments increased labile-P and moderately labile-P by 987% and 144%, respectively, and NPK treatment increased these factors by 823% and 125%, respectively, at the Chongqing site. At the Suining site, with NPKM treatment, increases in labile-P and moderately labile-P were 706% and 73%, respectively, and with NPK treatment, the increases were 529% and 47%, respectively. In contrast, non-labile-P was significantly decreased with NPKM treatment in comparison to that with NPK and CK treatments. Moreover, increases in soil C:N and C:P ratios decreased the labile-P pools and increased non-labile-P pools. A path analysis indicated that soil C:N:P stoichiometry indirectly controlled P uptake by directly affecting P transformation from non-labile to labile-P pools. Moreover, the non-labile-P in soil with high SOM and P content directly affected P uptake, indicating that soil P transformation is mainly driven by soil C and P in paddy soil. In conclusion, understanding mechanism of P mobility influenced by soil C:N:P stoichiometry could be helpful to manage soil P fertility under long-term fertilization in paddy soils of these regions.

Cost Effectiveness of Sweet Potato Production Using Farmyard Manure and Inorganic Phosphorus Fertilizer at Assosa Western Ethiopia

Sweet potato is one of the food security crop which has been cultivated in the South west, eastern and southern parts of Ethiopia over centuries. Despite that, the yield is below its genetic potential. This is due to less attention given to the crop in the region assuming that there is no response of the crop to fertilizers. A study was conducted to evaluate economic cost effectiveness of using farm yard manure and phosphorus fertilizer for sweet potato production in the study area. The treatment consisted of four levels of farm yard manure (0, 5, 10 and 15 t ha-1) and four levels of P (0, 23, 46 and 69 kg P2O5 ha-1). The experiment was laid out as a Randomized Complete Block Design in a factorial arrangement and replicated three times. Analysis of the result showed that using the rate of the combined fertilizers (15tha-1 farmyard manure and 69kg ha-1 phosphorus) gave the highest yield (23.65tha-1) which gave the highest net benefit of 60033Birr ha-1. Therefore, if the farmers use by integrating 15 t ha-1 farm yard manure and 69 kg P2O5 ha-1, they can be more profitable in the study area.

Nutrient Mineralization from Nitrogen- and Phosphorus-Enriched Poultry Manure Compost in an Ultisol

ABSTRACTThe combination of inorganic fertilizers and compost is a technique aimed at improving crop growth and maintaining soil health. Understanding the rate of nutrient release from enriched compost is important for effective nutrient management. A laboratory incubation study was conducted for 112 days to study the nutrient mineralization pattern of poultry manure compost enriched with inorganic nitrogen (N) and phosphorus (P) fertilizer nutrients in an Ultisol. Compost applied at the rate of either 5 or 10 g kg−1 was blended with N (50 kg N ha−1) and P (30 kg P ha−1). Carbon dioxide evolution and N and P mineralization were measured fortnightly. The bacterial and fungal populations were determined at the mid and end of the experiment. The combination of compost and inorganic N and P increased carbon (C) and P mineralization by 4−8% and 56−289%, respectively, over the application of either compost or inorganic N and P. However, P addition influenced the amount of C mineralized. Inorganic N and P, on the other hand, were better at increasing N mineralization than compost blended with inorganic N and P over a short time. The addition of compost stimulated bacterial and actinomycete populations, while fungal populations were unaffected. Actinomycetes and bacteria had similar and higher relationship trend with C (R2 = 0.24) and P (R2 = 0.47) mineralization and were key determinants in nutrient mineralization from compost in this Ultisol. Integrating compost with inorganic fertilizers improves nutrient availability through the growth and activities of beneficial microorganisms.

Effect of coal and wood ash on phosphorus immobilization in different textured soils

Decreased phosphorus (P) losses and improved environmental quality are crucial to consider while recycling farm wastes and adding various soil amendments. This study investigated the impact of coal and wood ash on the extractability of P from soils (sandy loam and loamy sand) amended with organic and inorganic phosphorus fertilizers. These soils were further amended coal and wood ash, and analyses were carried out to quantify the water-, Olsen-, and Mehlich 1-extractable P. Ratio of the ashes applied to soils were 5% to sandy loam soil while 10% to loamy sand soil. Water-extractable P was observed to be mainly dependent on the ash type as well as the extraction method. Ash amendment reduced the solubilization of P across soils up to 9% and 23% and 7% to 17% upon 5% and 10% ash amendment in loamy sand and sandy loam soils, respectively. However, the water-extractable P was found to be low in wood ash-amended soil as compared to coal ash. Interestingly, this extractability was greater in soils treated with inorganic P. Phosphorus extraction from soil followed the trend as Mehlich 1 > Olsen > water. P leachability was found to be mainly dependent on ash amendment but values were high for the soil treated with inorganic P. The study inferred that using ash materials such as coal ash and wood ash can be a practical measure for moderating P losses from soils important for economic and environmental perspectives.

Agrobacterium rhizogenes transformed soybeans with AtPAP18 gene show enhanced phosphorus uptake and biomass production

ABSTRACTLow-phosphorus stress is a challenging factor in limiting plant development. Soybean is cultivated in soils often low in phosphorus. However, on average 65% of total P is in the form of organic phosphates, which are unavailable to plants unless hydrolyzed to release inorganic phosphate. One approach for enhancing crop P acquisition from organic P sources is boosting the activity of acid phosphatases (APases). This study seeks to understand the role of an Arabidopsis (Arabidopsis thaliana) purple APase gene (AtPAP18) in soybean. Thus, the gene was isolated and a final vector (AtPAP18/pK7GWG2D) was built. Composite soybean plants were created using Agrobacterium rhizogenes-mediated transformation. A. rhizogenes K599 carrying the AtPAP18/pK7GWG2D vector with egfp as a reporter gene was used for soybean hairy root transformation. Analysis of Egfp expression detected fluorescence signals in transgenic roots, whereas there was no detectable fluorescence in control hairy roots. The enzyme assay showed that the APase activity increased by 2-fold in transgenic hairy roots. The transformed hairy roots displayed an increase in plant soluble P and total P contents, as compared with the control plants, leading to improved biomass production. RT-PCR analysis revealed high expression levels of AtPAP18 in transformed hairy roots. It is noteworthy that these primers amplified no PAP18 transcript in control hairy roots. Taken together, the findings demonstrated that overexpression of the AtPAP18 gene offers an operative tactic to reduce the utilization of inorganic phosphorus (Pi) fertilizer through increased acquisition of soil Pi, especially improving the crop yield on soils low in available P.