Use Of Phosphorus Fertilizers Research Articles

Phosphorus fertiliser application and the subsequent cadmium input in three provinces along Yangtze River region of China

ABSTRACT This study has undertaken an analysis of phosphorus fertiliser use in three provinces from 2010 to 2020: Sichuan, Hubei and Jiangsu along the Yangtze River basin. It was revealed that phosphorus fertiliser application rate of Hubei experienced the most significant reduction, and the application rate of Sichuan was the lowest, but its yield of different crops hardly decreased. The yield for all food crops by Jiangsu was highest, indicating the importance of strong economic development on sustainable agriculture practice. Cd input for Hubei was highest. In Jiangsu, Xuzhou, Lianyungang, and Suqian are the three cities applying the most phosphorus fertiliser, which also happen to be the cities with lowest GDP. The findings of this research could provide useful insights into the current practice of phosphorus fertiliser application in the main rice planting regions of China and facilitate the optimal use of global sustainable intensification of agricultural systems.

Phosphorus applications adjusted to optimal crop yields can help sustain global phosphorus reserves

With the longevity of phosphorus reserves uncertain, distributing phosphorus to meet food production needs is a global challenge. Here we match plant-available soil Olsen phosphorus concentrations to thresholds for optimal productivity of improved grassland and 28 of the world’s most widely grown and valuable crops. We find more land (73%) below optimal production thresholds than above. We calculate that an initial capital application of 56,954 kt could boost soil Olsen phosphorus to their threshold concentrations and that 28,067 kt yr−1 (17,500 kt yr−1 to cropland) could maintain these thresholds. Without additional reserves becoming available, it would take 454 years at the current rate of application (20,500 kt yr−1) to exhaust estimated reserves (2020 value), compared with 531 years at our estimated maintenance rate and 469 years if phosphorus deficits were alleviated. More judicious use of phosphorus fertilizers to account for soil Olsen phosphorus can help achieve optimal production without accelerating the depletion of phosphorus reserves.

The Use of Magnesium Fertilizer Can Improve the Nutrient Uptake, Yield, and Quality of Rice in Liaoning Province

In this study, the effects of the soil application and foliar spraying with magnesium fertilizers on rice yield and quality in Liaoning Province were investigated. Field experiments were conducted at Kaiyuan, Xinmin, and Dawa in 2022 and 2023. Magnesium fertilizers were used in the soil as magnesium sulfate monohydrate and silicon–magnesium fertilizer and on leaves was magnesium sulfate heptahydrate. The results showed that the application of 12 kg magnesium hm−2 in the soil at the Kaiyuan site can significantly increase rice yield by 14.8% compared with sites without magnesium fertilizer. The use of silicon–magnesium fertilizer showed a more obvious yield increase of 22.2%. The application of 3 kg magnesium hm−2 or 6 kg magnesium hm−2 on the leaf surface increased the rice yield at Kaiyuan by 19.4% and 21.6% and at Xinmin by 17.8% and 5.4%, respectively. The yield increase was more significant under the optimal fertilization treatment compared with the conventional fertilization treatment. The application of magnesium fertilizer increased the magnesium, nitrogen, and phosphorus contents in rice shoots and the potassium and crude protein contents in rice grains. The effect of foliar spraying with magnesium fertilizers was more obvious than soil application. Therefore, the magnesium fertilizer used on the leaf surface plays an important role in improving rice yield and quality in rice-growing areas with relatively rich soil magnesium content. Magnesium fertilizer can compensate for the yield decrease caused by the reduced use of nitrogen and phosphorus fertilizers by promoting nitrogen and phosphorus absorption in rice. Conclusively, the application of magnesium fertilizer is a promising measure to improve rice production in Liaoning province under a reduced nitrogen and phosphate fertilizer background.

Divergent responses of phosphorus solubilizing bacteria with P-laden biochar for enhancing nutrient recovery, growth, and yield of canola (Brassica napus L.)

The growing global population has led to a heightened need for food production, and this rise in agricultural activity is closely tied to the application of phosphorus-based fertilizers, which contributes to the depletion of rock phosphate (RP) reserves. Considering the limited P reserves, different approaches were conducted previously for P removal from waste streams, while the adsorption of ions is a novel strategy with more applicability. In this study, a comprehensive method was employed to recover phosphorus from wastewater by utilizing biochar engineered with minerals such as calcium, magnesium, and iron. Elemental analysis of the wastewater following a batch experiment indicated the efficiency of the engineered biochar as an adsorbent. Subsequently, the phosphorus-enriched biochar, hereinafter (PL-BCsb), obtained from the wastewater, underwent further analysis through FTIR, XRD, and nutritional assessments. The results revealed that the PL-BCsb contained four times higher (1.82%) P contents which further reused as a fertilizer supplementation for Brassica napus L growth. PL-BCsb showed citric acid (34.03%), Olsen solution (10.99%), and water soluble (1.74%) P desorption. Additionally, phosphorous solubilizing bacteria (PSB) were incorporated with PL-BCsb along two P fertilizer levels P45 (45 kg ha−1) and P90 (90 kg ha−1) for evaluation of phosphorus reuse efficiency. Integrated application of PL-BCsb with half of the suggested amount of P45 (45 kg ha−1) and PSB increased growth, production, physiological, biochemical, and nutritional qualities of canola by almost two folds when compared to control. Similarly, it also improved soil microbial biomass carbon up to four times, alkaline and acid phosphatases activities both by one and half times respectively as compared to control P (0). Furthermore, this investigation demonstrated that waste-to-fertilizer technology enhanced the phosphorus fertilizer use efficiency by 55–60% while reducing phosphorus losses into water streams by 90%. These results have significant implications for reducing eutrophication, making it a promising approach for mitigating environmental pollution and addressing climate change.

Optimizing phosphorus fertilizer use to enhance water quality, food security and social equality

There are large regional differences regarding the use of phosphorus (P) fertilizer in global crop production. Likewise, people's accesses to crop calories and exposure to water pollution differ largely among world regions. The use of P fertilizer is needed to meet agricultural requirement and solve these inequalities. We developed a multi-objective framework for optimizing P fertilizer use that considered water quality, food security and social equality. Different optimal objectives yield contrasting results for the geographical distribution of P fertilizer use, crop calorie production and social equality. Optimized P fertilizer use without recycling P management may pose a threat to global food security. Approximately 3 %–43 % of the current global crop calorie production may be decreased, and inequality in access to crop calories may also increase. Overall, although a multi-objective framework to optimize the use of P fertilizer reduces crop calorie yield, it can help intergenerational equality of P fertilizer use and improve water quality.

Transcriptome analysis of axillary buds in low phosphorus stress and functional analysis of TaWRKY74s in wheat

BackgroundWheat is one of the main grain crops in the world, and the tiller number is a key factor affecting the yield of wheat. Phosphorus is an essential element for tiller development in wheat. However, due to decreasing phosphorus content in soil, there has been increasing use of phosphorus fertilizer, while imposing risk of soil and water pollution. Hence, it is important to identify low phosphorus tolerance genes and utilize them for stress resistance breeding in wheat.ResultsWe subjected the wheat variety Kenong 199 (KN199) to low phosphorus stress and observed a reduced tiller number. Using transcriptome analysis, we identified 1651 upregulated genes and 827 downregulated of genes after low phosphorus stress. The differentially expressed genes were found to be enriched in the enzyme activity regulation related to phosphorus, hormone signal transduction, and ion transmembrane transport. Furthermore, the transcription factor analysis revealed that TaWRKY74s were important for low phosphorus tolerance. TaWRKY74s have three alleles: TaWRKY74-A, TaWRKY74-B, and TaWRKY74-D, and they all belong to the WRKY family with conserved WRKYGQK motifs. These proteins were found to be located in the nucleus, and they were expressed in axillary meristem, shoot apical meristem(SAM), young leaves, leaf primordium, and spikelet primordium. The evolutionary tree showed that TaWRKY74s were closely related to OsWRKY74s in rice. Moreover, TaWRKY74s-RNAi transgenic plants displayed significantly fewer tillers compared to wild-type plants under normal conditions. Additionally, the tiller numebr of the RNAi transgenic plants was also significantly lower than that of the wild-type plants under low-phosphorus stress, and increased the decrease amplitude. This suggestd that TaWRKY74s are related to phosphorus response and can affect the tiller number of wheat.ConclusionsThe results of this research showed that TaWRKY74s were key genes in wheat response to low phosphorus stress, which might regulate wheat tiller number through abscisic acid (ABA) and auxin signal transduction pathways. This research lays the foundation for further investigating the mechanism of TaWRKY74s in the low phosphorus environments and is significant for wheat stress resistance breeding.

Optimizing Phosphorus Fertilizer Use on the Loess Plateau: Impact on Soil Properties and Crop Production Efficiency

Various phosphorus (P) fertilizers are commonly utilized in agricultural production on the Loess Plateau. However, there exists a widespread issue of improper matching between P fertilizers, crop types, and soil types. This study proposes a scientifically based approach to managing phosphate fertilizer through a matching experiment. A field experiment was conducted to investigate the effects of different P fertilizers on soil P profiles in a wheat–corn rotation between October 2017 and September 2021. The experiment adopted a randomized block design. P fertilizer was applied as a basal fertilizer at rates of 115 kg P2O5 ha−1 during the wheat season and 90 kg P2O5 ha−1 during the maize season. Nitrogen (N) fertilizer application rates were 120 kg N ha−1 for wheat and 180 kg N ha−1 for maize. N fertilizer was divided into two applications, with 60% applied at pre-planting and 40% at the jointing stage of wheat or the V12 stage of maize. P fertilizer variants utilized in the study included ammonium dihydrogen, ammonium phosphate, calcium-magnesia phosphate fertilizer, calcium superphosphate, and ammonium polyphosphate. The transformation process of phosphate was examined, revealing that the commonly considered dominant diammonium phosphate fertilizer was not the optimal choice in this production system. Ammonium polyphosphate, calcium superphosphate, and ammonium dihydrogen were deemed more suitable for application in Loess soil. Furthermore, an analysis was conducted on the relationship between P fractions, soil properties, and soil Olsen-P. This research emphasizes the significance of strategic phosphate fertilizer use in agriculture to ensure efficient production and to help address the global P scarcity.

Potassium and Micronutrient Fertilization for Enhancement of Tef Yield in Vertisols of Hawzen and Enderta Districts, Tigray Region, Ethiopia

Field study was conducted in Enderta and Hawzen districts of Tigray region on six farmers’ fields aimed at evaluating potassium and micro-nutrient effect on yield and yield components of the tested crop. The experiment comprised of eight treatments including control and recommended NP arranged in Randomized Complete Block Design with two replications. Phosphorus fertilizers were applied at planting, while the nitrogen fertilizer was applied in two splits. The micronutrients and Typrosine were applied in foliar forms. SAS version 9 statistical software was used for data analysis. The analyzed results depicted that Tef yield was increased with potassium and micro-nutrient application in both districts mathematically even though it was not consistent. In line to this, the highest grain and straw yields of Tef was recorded at recommended NP with application of 50 kg/ha K2SO4 and recommended NP with a foliar application of Typrosine, respectively. But this result was statistically similar with the recommended NP. Thus, application of additional fertilizer without yield increment is uneconomical rather than maximizing costs. Hence, potassium, copper, and zinc in the current sources were not Tef yield limiting nutrients in the study sites even though the soil statuses are low. On the other hand nitrogen and phosphorus were observed the Tef yield limiting nutrients in this study. For this reason maximizing the use of nitrogen and phosphorus fertilizers with detailed research on its level and their interactions, sources and application times is important to maximize the Tef productivity in the Vertisols of Enderta and Hawzen district.

Respon Pertumbuhan dan Hasil Tanaman Jagung (Zea Mays L.)Terhadap Pemberian Pupuk Majemuk P dan K

The use of phosphorus and potassium compound fertilizers has become a commonly used strategy in modern agricultural practices to increase crop yields, optimize land use, and minimize environmental impacts. This study aims to determine the effect of applying a combination of PK (53–34) compound fertilizer doses on increasing the growth and yield of maize (Zea mays L.). This research was conducted at the Experimental Garden of the Faculty of Agriculture, Jatinangor Campus, Sumedang Regency, West Java. The altitude of the place is about 750 meters above sea level. The method in this study used a randomized group design (RAK) with ten treatments and three replications. Treatment A (Control), (B) Standard fertilizer (Urea, SP-36, and KCl), (C) 1 Urea + 1/2 PK, (D) 1 Urea + 1 PK, (E) 1 Urea + 1 ½ PK, (F) 3/4 Urea + ½ PK, (G) 3/4 Urea + 1 PK, (H) 3/4 + 1 ½ PK, (I) ½ Urea + 1 PK, and (J) 1 PK. The results showed that the doses of urea fertilizer (225 kg ha-1) and PK compound (60 kg ha-1) gave the best results on plant height, number of leaves, cob length, cob diameter, cob weight with cob, cob weight without cob, and weight per hectare.

Using Bacillus megaterium as a bio-fertilizer alleviates salt stress, improves phosphorus nutrition, and increases cauliflower yield

The traditional crop production system involves the use of large amounts of chemical fertilizers, which negatively impacts the ecological environment by increasing soil degradation and salinity, threatening sustainable agricultural production. Therefore, there is an urgent need for agricultural practices that increase plant productivity and reduce negative impacts on the environment. Phosphate-solubilizing microorganisms can enhance nutrient availability and plant uptake. This study investigated the effect of Bacillus megaterium as a bio-fertilizer (inoculated and non-inoculated) combined with phosphorus fertilizer (40, 60, and 80 kg. ha−1) on the growth and yield of cauliflower grown under saline conditions, saline soil (9.68 dS.m−1) and saline irrigation water (7.12 dS.m−1). Salt-stressed cauliflower inoculated with Bacillus and fertilized with 60 or 80 kg. ha−1 P2O5 showed improved growth and higher yield compared to other treatments, without significant differences between them. However, Bacillus-treated plants fertilized with 60 P2O5 showed increases in superoxide dismutase (SOD) by 29.3%, catalase (CAT) by 13.9, chlorophyll by 10.4%, N by 7.8%, and P by 8.6%, while Na decreased by 7.8%, resulting in significant increases in cauliflower yield (head weight by 9.3%, and total yield by 8.3%) compared with the control treatment (recommended P fertilizer, 80 kg P2O5. ha−1). The results indicated that the inoculation of salt-stressed plants with Bacillus megaterium is a promising and feasible approach to reduce phosphorus fertilizer use by up to 25% and enhance membrane stability (MSI), relative water content (RWC), nutrient availability, and growth performance, thus mitigating the adverse effects of salt stress exacerbated by climate change.

Аналіз лінійно-вагових показників річкових раків (Astacus) у водоймах Дніпропетровської області

This research focuses on studying the narrow-clawed crayfish in the Dnipropetrovsk region. The narrow-clawed crayfish, Astacus leptodactylus, is a crucial component of industrial fisheries and plays a significant role in the development of aquatic ecosystems. Within the territory of the Dnipropetrovsk region, crayfish inhabit various freshwater bodies, including rivers, lakes, floodplains, and ponds. It is known that water bodies in the Dnipro region undergo substantial anthropogenic impact, leading to alterations in the life cycles and reproductive features of hydrobionts. Investigated areas of reservoirs were characterized by diverse levels and factors of pollution, such as contamination of water with chemical and radioactive substances, oil products, wastewater, and the use of nitrogen and phosphorus fertilizers. These anthropogenic interventions may result in a decrease in populations of aquatic organisms, posing a serious threat to water ecosystems. The sensitivity to environmental changes makes crayfish a valuable bioindicator species. Fertility indicators and morphometric characteristics can be considered as bioindicators. The analysis of linear-weight parameters revealed that crayfish extracted from the Zaporizhzhia Reservoir had a body length 15–18% greater than those from the Kamianske and Samara Bay. Additionally, they exhibited larger cephalothorax dimensions by 18–20%, and their mass was almost 50% higher compared to individuals from other water bodies. Samara Bay demonstrated significantly lower fertility indicators compared to the Zaporizhzhia Reservoir, with crayfish fertility being reliably 63% lower. The established differences in morphometric indicators between crayfish from the Zaporizhzhia Reservoir, Samara Bay and Kamianske Reservoir may indicate heterogeneity in the living conditions within the water bodies of Dnipropetrovsk and might be induced by anthropogenic pressures.

Evaluation of Variable Application Rate of Fertilizers Based on Site-Specific Management Zones for Winter Wheat in Small-Scale Farming

China is currently experiencing a severe issue of excessive fertilization. Variable rate fertilization (VRF) technology is key to solving this issue in precision agriculture, and one way to implement VRF is through management zone (MZ) delineation. This study is aimed at evaluating the feasibility and potential benefits of VRF based on site-specific MZs in smallholder farm fields. This study determined the amounts of basal and top-dressing fertilizers in different spatial units, based on soil nutrient MZs and crop growth MZs, respectively. The potential agronomic, economic, and environmental advantages of spatial variable rate fertilization were further assessed by comparing the farmer’s treatment, the expert’s treatment, and the variable rate fertilization treatment based on management zones (VR-MZ). The results showed that VR-MZ reduced the use of nitrogen (N), phosphorus (P), and potassium (K) fertilizers by 22.90–43.95%, 59.11–100%, and 8.21–100%, respectively, and it also increased the use efficiency of N, P, and K by 12.27–28.71, 89.64–176.85, and 5.48–266.89 kg/kg, respectively, without yield loss. The net incomes of VR-MZ were 15.5–449.61 USD ha−1 higher than that of traditional spatially uniform rate fertilization. Meanwhile, less nitrous oxide emission (23.50–45.81%), ammonia volatilization (19.38–51.60%), and nitrate ion leaching amounts (28.77–53.98%) were found in VR-MZ compared to those in uniform fertilization. The results suggest that the VR-MZ has great potential for saving fertilizers, significantly increasing farmers’ net income, reducing environmental pollution, and promoting the sustainable use of resources. This study provides a theoretical basis and technical support for exploring a VRF suitable for village-scale farming.

Promotion of phosphate release from humic acid-iron hydroxide coprecipitates in the presence of citric acid

Phosphate (P) resources are expected to be depleted within a century. Therefore, promoting balanced phosphorus fertilizer use and understanding phosphorus dynamics in soils containing iron (III), organic acids, and iron (III)-organic molecule particulates is crucial. This study investigated the sorption of citric acid onto humic acid-iron hydr(o)xide coprecipitate (HAFHCP) and the reciprocal effects of citric acid and P sorption on HAFHCP with different C/Fe ratios. The results showed that the maximum sorption capacity (MSC) of citric acid on HAFHCP decreased with increasing C/Fe ratios in the HAFHCP. The P sorption on HAFHCP pre-sorbed with citric acids (denoted as C–P) decreased by 50% compared with that of the MSC on FH. However, citric acids could only reduce P sorption by 20% when P was pre-sorbed on HAFHCP (denoted as P–C). The results suggested that upon the formation of HAFHCP, citric acids might increase P availability, especially in the C–P system. Although citric acids initially inhibited P sorption on HAFHCP in the P–C system, P sorption increased with prolonged reaction time. The exposures of new sorption sites upon dissolution of Fe from HAFHCP by citric acids or/and the formations of Fe bridge between P and organic domains of HAFHCP might contribute to these results. Additionally, a number of large HAFHCP aggregates became smaller while sorbing P due to the increasing electric repulsion on the surfaces of FH, enabling the subsequent dissolutions of more Fe by citric acids from HAFHCP in the P–C system. By integrating these innovative and sustainable strategies, the recycling and reuse of P can be optimized, thereby minimizing the reliance on synthetic fertilizers and mitigating environmental impacts. This approach fosters the efficient utilization of phosphorus resources, improves soil fertility, and enhances the overall resilience of agricultural systems and ecosystems.

Increase the Efficient Use of Phosphorus Fertilizer for Maize in the Calcareous Soils

ABSTRACT Phosphorus (P) is one of the 17 essential plant nutrients, and it is critical for plant metabolism, photosynthesis, and growth. P fertilizers are also critical for crop production and global food security. Type and application method of P fertilizer may lead to increased P accumulation and crop production in the Ganges delta soils. The aim of the present study is to increase the P use efficiency (PUE) by two different P application methods for maize cultivation. The experiment comprised a factorial combination of two methods (broadcasting and furrow placement) and three rates of P fertilizer (36, 48, and 60 kg P/ha). Considering P application methods, furrow placement gave 8.66–27.92% yield benefit over broadcasting method. Maize yield, PUE by crop plant, partial factor productivity, economic efficiency, and P concentration in leaf were remarkably higher in furrow placement than conventional broadcasting method of P application. The furrow placement exhibited higher yield at lower rate of P application (36 and 48 kg P/ha), while no significant changes were observed for grain yield between two methods for high P rate (60 kg/ha). Thus, it is concluded that furrow placement of P application at 36 and 48 kg/ha would give the best grain yield of maize in the Ganges delta floodplain soils.

Tracing the sources and transport of the total phosphorus in the upper Yangtze River

Deterioration of water quality is a significant challenge in basin management, posing a serious threat to global water security. In this study, a water quality model named Spatially Referenced Regressions on Watershed Attributes (SPARROW) was applied to quantify the total phosphorus (TP) loads from different sources and investigate the transport processes for the entire upper Yangtze River Basin. The results showed that the phosphate fertilizer use was the main source of TP loads (67.7%), followed by livestock and poultry breeding source (17.6%), point source (10.5%), and rural life source (4.2%), and the phosphorus fertilizer use source dominated the overall spatial distribution pattern of the TP loads. The transport of the TP loads was further traced, and the results showed that 30% of TP loads were retained in the upper reaches of Yangtze River. A total of 7.4% of the river reaches exceeded the water quality management standards, and they could be restored by reducing 60% of phosphate fertilizer use and point sources in their sub-basins according to scenario simulations. Results revealed that controlling TP sources was effective to improve water quality. This study provides a reference for accurately controlling nutrients in other river basins.

Influence of the Joint Use of Phosphorus and Magnesium Fertilizers on the Background of Nitrogen and Potassium Fertilizers on the Productivity, Quality and Removal of Nutrition Elements in Spring Barley Depending on the Acidity of Sod-Podzolic Soil

In the long term (56 years) field experience revealed a great return from the combined use of lime, phosphorus and magnesium fertilizers compared with the background of nitrogen-potassium fertilizers on strongly acidic sod-podzolic poorly cultivated soil, with a high content of mobile aluminum in it (up to 130 mg/kg), due to the prolonged use of physiologically acidic fertilizers in the form of ammonium nitrate and potassium chloride. The use of phosphorous fertilizers on highly acidic untreated soil contributed to an increase in the yield of spring barley by 67%, on medium-acidic soil produced at a dose of 11.5 t CaCO3/ha – by 2.3 times, on slightly acidic soil produced at a dose of 19.0 t CaCO3/ha – by 2.6 times, when combined with magnesium fertilizers – by 2.5 and 2.9 times, respectively, according to compared with the yield on the background of nitrogen-potash fertilizers 1.78 t/ha (highly acidic soil). With the introduction of magnesium fertilizers on slightly acidic soil, the payback by adding grain of mineral fertilizers (N90P60K90) increased by 3 times, increasing to 13.9 kg/kg, with an increase in protein content compared to the background of nitrogen-potassium fertilizers by 1.2%. The use of nitrogen and phosphorus by spring barley plants increased 3.4 times, potassium – 3.0 times.

The influence of the aftereffect of long-term use of mineral fertilizers on sorghum grain productivity and quality on ordinary blackearth of the Central Pre-Caucasus

There have been presented the study results of the experiment of the Geographical Network of Experiments with fertilizers, established in 1975 on ordinary chernozem under conditions of unstable moisture in the Stavropol Territory. The purpose of the current study was to reveal the influence of the aftereffect of the long-term use of mineral fertilizers on the agrochemical properties of soil, productivity, and quality of sorghum grain, depending on the weather conditions of the year. There has been established that, after 30 years of action and 14 years of aftereffect of the use of phosphorus fertilizers in doses of 60–180 kg/ha of a.i. the content of residual phosphorus in the soil layer of 0–20 cm before sowing sorghum varied from 25 to 55 mg/kg. The crop productivity was closely dependent on weather conditions and the agrochemical condition of the soil. In arid conditions in 2020, the largest grain productivity (2.5–3.16 t/ha) was obtained in areas of phosphorus fertilizer’s aftereffect with a high content of P2O5 in soil (more than 30 mg/kg). In the wet year, the largest productivity (5.10–5.64 t/ha) were obtained in nitrogen fertilizers’ aftereffect against the background of low phosphates availability (12–16 mg/kg). In different weather conditions, the maximum level of sorghum productivity was obtained in the aftereffect of complete mineral fertilizer or with a balanced nutrient regime of the soil, in 2020 it was 3.81–4.96 t/ha and in 2022 it was 5.4–6.14 t/ha. Sorghum grain quality was also determined by the weather and soil properties. Grain with the highest crude protein percentage (9.9–13.6 %) was obtained in a dry year after the effect of nitrogen fertilizer. In both years of the study, the products obtained after the application of high doses of one phosphorus fertilizer (120–180 kg/ha a.i.) had the least nutritional value. The crude protein percentage in grain did not exceed 2.2–7.8 %. To stabilize productivity and increase the nutritional value of sorghum, it is necessary, first of all, to optimize the nitrogen nutrition of plants, especially in conditions of good moisture supply.

Long-Term Organic Manure Substitution Increases Yield and Phosphorus Use Efficiency in a Double-Rice System by Altering Soil Phosphorus Uptake and Apparent Balance

The excessive use of chemical phosphorus (P) fertilizer can lower grain yield and P use efficiency (PUE) by aggravating soil acidity. Substituting organic manure for chemical fertilizer can alleviate the problem, although the long-term effect of organic manure incorporation is unknown. We conceptualized that substituting organic manure for chemical fertilizer may result in higher crop yields and PUE. Therefore, the impact of long-term fertilizer treatments: (i) CK (control), (ii) PK (phosphorus and potassium fertilizer), (iii) NP (nitrogen and P fertilizer), (iv) NK fertilizer, (v) NPK fertilizer, and (vi) NPKM (30% NPK fertilizer plus 70% manure) on rice yield, PUE, P uptake, and apparent balance (APB) was investigated. The results showed that rice yield under different fertilizer treatments ranged from 6.2 to 11.8 t ha−1 (1984–1995), 7.9 to 12.7 t ha−1 (1996–2007), and 6.6 to 12.8 t ha−1 (2008–2018). The rice yield under NPKM was greatly improved compared to other treatments, except with that of NPK (1984–1995). Soil organic carbon (SOC), available P and phosphorus activation coefficient (PAC) under NPKM were significantly higher than other treatments during 1984–2018. Soil pH (1984–2018) was greatly higher under CK and NPKM than under other treatments. Soil total P under PK, NP, NPK, and NPKM was significantly higher than under CK and NK (1984–2018). Compared to other treatments, P uptake was significantly higher under NPKM, except with that of NPK (1984–1995 and 2008–2018). The average PUE (1984–2018) was 10.7, 20.2, 36.1, and 44.2 kg kg−1 under PK, NP, NPK, and NPKM, respectively. The APB under NPKM was significantly lower as compared to PK, NP, and NPK treatments. Therefore, we conclude that in addition to improving soil organic carbon, cations inputs from organic manure can be a factor for the increase in soil pH, making organic manure substitution for chemical fertilizer a more efficient strategy for increasing PUE and crop yield.

Soil phosphorus forms and fertilizer use efficiency are affected by tillage and soil acidity management

Liming combined with no-tillage (NT) can increase the efficiency of P use by accumulating soil P in more available forms and improving root exploration due to the absence of toxic Al3+. This study aimed to evaluate the long-term effect of different combinations of soil tillage managements and liming in a subtropical Oxisol on the accumulation of P forms, legacy P index, and P use efficiency. A long-term experiment was used, established in 1987 testing (i) conventional tillage with lime (lime-CT) and control (control-CT), (ii) NT with lime (lime-NT) and control (control-NT), and (iii) occasional tillage with lime (lime-OT). The NPK fertilization was the same for all treatments. The accumulated grain yield and P use efficiency of 56 crops between 1987 and 2019 were evaluated. In 2019, soil samples were collected in the 0–5, 5–10, and 10–20 cm layers and submitted to a sequential chemical fractionation of P, P indexes, and soil acidity parameters. The results reveal that is necessary to correct acidity to increase crop yields and P use efficiency, regardless of the soil management used. This increase is enhanced when soil acidity correction by liming is combined with the use of conservation systems such as NT. Furthermore, after liming with incorporation, liming can be done on the soil surface, without the need to repeat the operation of lime incorporation, ensuring high efficiency of P use even after more than four decades.

Strategies for Improving Cowpea Grain Yield in the Eastern Amazon: Biological Nitrogen Fixation, Phosphorus Nutrition, and Molybdenum Seed Enrichment

ABSTRACT This work aimed to evaluate the use of phosphorus (P) fertilizer, rhizobia inoculation, and seed enrichment with molybdenum (Mo) as tools for enhancing the cowpea yield in the Brazilian eastern Amazon. A set of field and greenhouse experiments were carried out in cerrado and upland forest environments. Four levels of P fertilization, eight rhizobia strains, and the application of mineral nitrogen (N) were evaluated for the cultivar BRS Tumucumaque (BR = Brasil e S = Sementes), and two levels of Mo seed enrichment were assessed for the cultivars BRS Tumucumaque and BRS Guariba. Grain yield increased linearly with the level of P applied. Inoculation with the rhizobia strain BR 3267 increased the shoot and nodule mass of the cultivar BRS Tumucumaque. There was no difference in grain yield and grain N accumulation between inoculation with seven rhizobia strains, N mineral fertilization and the control (without inoculation and N fertilization) in cerrado and upland forest environments. Cowpea grain yield and grain N accumulation were higher in the cerrado than in the upland forest environment and when the seeds were enriched with Mo. Phosphorus fertilization and seed enrichment with Mo are efficient tools to enhance cowpea yield in the Brazilian Amazon.