How Does Quinoa (Chenopodium quinoa Willd.) Respond to Phosphorus Fertilization and Irrigation Water Salinity?

Soil salinity is a major problem in arid and semi-arid regions, causing land degradation, desertification, and subsequently, food insecurity. Salt-affected soils and phosphorus (P) deficiency are the common problems in the sub-Sahara, including the Southern region of Morocco. Soil salinity limits plant growth by limiting water availability, causing a nutritional imbalance, and imparting osmotic stress in the plants. The objective of this study was to determine the positive effects of P on growth and productivity and understand the major leaf mineral nutrient content of quinoa (Chenopodium quinoa Willd.) cv. “ICBA Q5” irrigated with saline water. A field experiment applying three salinity (Electrical Conductivity, EC) levels of irrigation water (ECw = 5, 12, and 17 dS·m−1) and three P fertilizer rates (0, 60, and 70 kg of P2O5 ha−1) were evaluated in a split-plot design with three replications. The experiment was conducted in Foum El Oued, South of Morocco on sandy loam soil during the period of March–July 2020. The results showed that irrigation with saline water significantly reduced the final dry biomass, seed yield, harvest index, and crop water productivity of quinoa; however, P application under saline conditions minimized the effect of salinity and improved the yield. The application of 60 and 70 kg of P2O5 ha−1 increased (p < 0.05) the seed yield by 29 and 51% at low salinity (5 dS·m−1), by 16 and 2% at medium salinity (12 dS·m−1), and by 13 and 8% at high salinity (17 dS·m−1), respectively. The leaf Na+ and K+ content and Na+/K+ ratio increased with irrigation water salinity. However, the leaf content of Mg, Ca, Zn, and Fe decreased under high salinity. It was also found that increasing P fertilization improved the essential nutrient content and nutrient uptake. Our finding suggests that P application minimizes the adverse effects of high soil salinity and can be adopted as a coping strategy under saline conditions.

Effect of P fertilizer and precipitation on wheat under permanent beds in the absence of N fertilizer application

Environmental conditions contribute to a large percentage of wheat yield variability. This phenomenon is particularly true in rainfed environments and non-responsive soils to N. However, the effect of P application on wheat is unknown in the absence of N fertilizer application. This study was conducted from 2012 to 2019 in permanent beds established in 2005. Treatments were arranged in a split-plot design and consisted of superimposing three P treatments (foliar, banded and broadcast application) plus a check (0P) within each one of four preceding N treatments (applied from 2005 to 2009). Foliar P generally showed a greater response than granular P treatments even though the soil tests high P (>30 mg/kg). Precipitation estimated for two different growth intervals explained through regression procedures the Years' effect. Seasonal precipitation (224–407 mm) explained variation of relative yield, N harvest index (NHI) and P agronomic efficiency (AE). Reproductive stage precipitation (48–210 mm) explained soil N supply. In dry years, foliar P application improved predicted relative yield 14% and AE 155 kg grain/kg P compared to granular P treatments. Similarly, soil N supply increased 15 kg/ha in dry moisture conditions during the reproductive stage. The NHI consistently improved over the crop seasons. This improvement was relatively larger for 0 kg N/ha. On average, NHI increased from about 0.57 to 0.72%. Normalized difference vegetation index (NDVI) readings at the booting growth stage were negatively associated with NHI. Foliar P in this non-responsive soil to N showed the potential to replace granular P sources. However, the omission of granular P needs to be further studied to estimate the long-term effect on the soil P test.

Estimation of the P Fertilizer Demand of China Using the LePA Model

Modern phosphate (P) fertilizers are sourced from P rock reserves, a finite and dwindling resource. Globally, China is the largest producer and consumer of P fertilizer and will deplete its domestic reserves within 80 years. It is necessary to avoid excess P input in agriculture through estimating P demand. We used the legacy P assessment model (LePA) to estimate P demand based on soil P management at the county, regional, and country scales according to six P application rate scenarios: (1) rate in 2012 maintained; (2) current rate maintained in low-P counties and P input stopped in high-P counties until critical Olsen-P level (CP) is reached, after which rate equals P-removal; (3) rate decreased to 1–1.5 kg ha−1 year−1 in low-P counties after CP is reached and in high-P counties; (4) rate in each county decreased to 1–8 kg ha−1 year−1 after soil Olsen-P reached CP in low P counties; (5) rate in each county was kept at P-removal rate after reduction; (6) P input was kept at the rate lower than P-offtake rate after reduction. The results showed that the total P fertilizer demand of China was 750 MT P2O5, 54% of P fertilizer can be saved from 2013 to 2080 in China, and soil Olsen-P of all counties can satisfy the demand for high crop yields. The greatest potential to decrease P input was in Yangtze Plain and South China, which reached 60%. Our results provide a firm basis to analyze the depletion of P reserves in other countries.

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

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

Response of Normal and Low-Phytate Genotypes of Pea (Pisum sativum L.) on Phosphorus Foliar Fertilization

Phosphorus (P) is an important nutrient in plant nutrition. Its absorption by plants from the soil is influenced by many factors. Therefore, a foliar application of this nutrient could be utilized for the optimal nutrition state of plants. The premise of the study is that foliar application of phosphorus will increase the yield of normal-phytate (npa) cultivars (CDC Bronco a Cutlass) and low-phytate (lpa) lines (1-2347-144, 1-150-81) grown in soils with low phosphorus supply and affect seed quality depending on the ability of the pea to produce phytate. A graded application of phosphorus (H₃PO₄) in four doses: without P (P0), 27.3 mg P (P1), 54.5 mg P (P2), and 81.8 mg P/pot (P3) realized at the development stages of the 6th true leaf led to a significant increase of chlorophyll contents, and fluorescence parameters of chlorophyll expressing the CO2 assimilation velocity. The P fertilization increased the yield of seeds significantly, except the highest dose of phosphorus (P3) at which the yield of the npa cultivars was reduced. The line 1-2347-144 was the most sensible to the P application when the dose P3 increased the seed production by 42.1%. Only the lpa line 1-150-81 showed a decreased tendency in the phytate content at the stepped application of the P nutrition. Foliar application of phosphorus significantly increased ash material in seed, but did not tend to affect the protein and mineral content of seeds. Only the zinc content in seeds was significantly reduced by foliar application of P in npa and lpa pea genotypes. It is concluded from the present study that foliar phosphorus application could be an effective way to enhance the pea growth in P-deficient condition with a direct effect on seed yield and quality.

Crop Production and Phosphorus Legacy with Long-Term Phosphorus- and Nitrogen-Based Swine Manure Applications under Corn-Soybean Rotation

The traditional manure management strategy, based on crop N needs, results in accumulation of phosphorus (P) in soil due to the imbalance of N/P ratio between crop requirement and manure supply. This study was conducted from 2004 to 2013 to evaluate the effects of P-based liquid and solid swine manure (LMP and SMP, for P-based liquid and solid swine manure, respectively) application, in comparison with N-based application (LMN and SMN, for N-based liquid and solid swine manure, respectively), on crop yield and soil residual P under corn (Zea mays L.)–soybean (Glycine max L.) rotation in a Brookston clay loam soil of the Lake Erie basin, ON, Canada. Chemical fertilizer P (CFP) and non-P treatments were included as controls (CK). For liquid manure treatments, corn yield for LMN showed a lower annual corn yield (7.82 Mg ha−1) than LMP (9.36 Mg ha−1), and their differences were even statistically significant at p < 0.05 in some cropping years. The annual corn yield of LMP was also higher than those of SMP (7.45 Mg ha−1) and SMN (7.41 Mg ha−1), even the CFP (8.61 Mg ha−1), although the corresponding yield differences were not significant (p < 0.05) in some cropping years. For soybean, the plots with P application produced an average of 0.98 Mg ha−1 greater annual yields than CK. No significant differences were found between CFP and manure treatments. The annual corn yield of SMN was close to that of the CK (7.19 Mg ha−1). The grain P removal (GPR) of SMN (18.6 kg ha−1) for soybean was significantly higher than that of the other treatments. The above-ground-P uptake (AGPU) in SMN, for both corn and soybean, was significantly higher than that of the other five treatments. The soil test P (STP) presented clear stratification, concentrating in the top 30 cm soil depth after 10 years of application. The contents of STP with LMN and SMN increased from 7.1 mg P kg−1 to 12.4 and 45.5 mg P kg−1, respectively. The sum of STP mass (0–30 cm) with LMP (31.6 kg ha−1) was largely identical to that with CFP (30.1 kg ha−1); however, with SMN (173.7 kg ha−1), it was significantly higher than the rest of the treatments. Manure P source availability coefficients were averaged at 1.06 and 1.07 for LMP and SMP, respectively. The addition of phosphorus-based liquid or solid swine manure can overcome the drawback of traditional N-based applications by potentially reducing the adverse impact on water quality while sustaining crop agronomic production.

Short-chain soluble polyphosphate fertilizers increased soil P availability and mobility by reducing P fixation in two contrasting calcareous soils

Short-chain polyphosphate fertilizers have been increasingly applied in agriculture, but little is known about the chemical behaviors of polyphosphate in soils. Herein, a cylinder experiment was carried out to investigate the influences of different P types (i.e., mono-ammonium phosphate (MAP), phosphoric acid (PA) and ammonium polyphosphate (poly-P)) and their application methods (single vs split) on the mobility and availability of P in soil through a column millimeter-scale slice cutting method; meanwhile a soil microcosm experiment (560-day) was conducted to investigate the effects of different P types on phosphorus dynamic transformation. Polyphosphate addition significantly increased P mobility. The average distance of P downward movement (81.5 mm) in soil profile in the poly-P application treatment increased by 33.6% and 81.1%, respectively, compared to the MAP and PA treatments. Different P application methods also markedly influenced phosphorus mobility. For instance, the average distance of P vertical movement in the split P application treatment was 21.2% higher than in the single application treatment, indicating that split P addition significantly increased P downward movement. Moreover, polyphosphate application decreased soil P fixation by blocking the transformation of the applied-P from labile to recalcitrant forms (HCl-P and residual-P). Overall, our findings provide meaningful information to current phosphorus fertilization practice in increasing soil P mobility and bioavailability. We suggest that polyphosphate could be regarded as an alternative P source used in agriculture, and split polyphosphate application is recommended as an effective P fertilization strategy.

EFFECTS OF PHOSPHORUS AVAILABILITY ON NODULATION AND NITROGEN UPTAKE BY THREE LEGUME CROPS IN TWO GHANAIAN SOILS

Purpose: A greenhouse study of Soybean, Cowpea and Pigeon Pea was made at University of Ghana, to determine the effects of phosphorus availability on nodulation and nitrogen uptake by the afore mentioned legumes in two Ghanaian soils, Adenta and Nzema series. Methodology: Three P rates of 0mg, 50mg and 100mg P of TSP and TPR were applied to a kilogram of soil per pot in two soil series. The pots were arranged using Randomized Complete Block Design. GenstatR was used to do the statistical analysis. Findings: The results from this study showed that with or without Triple Super Phosphate (TSP) or Togo Phosphate Rock (TPR), soybean did not form nodules in the Nzema soil but nodulated with TSP application in the Adenta soil. The absence of nodulation even with high P from TSP by soybean in Nzema soil is surprising but the observation in the Nzema soil may be attributed to the absence of soybean Rhizobium cells or insignificant numbers of these rhizobia. The results of the present data indicated that treatments with higher P application gave higher N uptake and showed the link among P application, high nodule dry weight, and N uptake. The improvement in the dry matter yield of pigeon pea and cowpea on Adenta soil and soybean on the Nzema soil at TPR50 and TPR100 show the importance of P application to dry matter yield of legumes. Significant difference that was shown by cowpea on Nzema soil could be attributed to the ability of the crop to desorp P from sparingly available P sources through exudation of high amounts of organic acid anions, mainly citrate. Unique contributions to theory, practice and policy: In the soil, Rhizobium species must recognize their specific host before nodulation may take place and the absence of the appropriate Rhizobium species with the introduction of a legume into a given soil may result in no or poor nodulation. Low P availability is a challenge for crop species to nodulate since the rhizobia responsible for nitrogen fixation have a high P requirement. The toxicity of Aluminum to rhizobia may be due to inhibition of DNA replication because of binding of Aluminum to DNA. One factor that could have accounted for the better nodulation in soil is the higher acidity. The optimum pH for effective rhizobia growth in soils is between pH 6 and 7.

Preparing for tenure and promotion at PUI institutions

In this paper, we discuss the importance for faculty to become familiar with the general guidelines for collecting, assembling and preparing a tenure and promotion (T&P) application or dossier at a Primarily Undergraduate Institution (PUI) and the critical role that mentoring plays throughout the T&P process. While key elements of the application process such as submission timelines and documentation guidelines are usually outlined in the faculty handbook of the specific institution, many aspects of assembling the dossier are not necessarily detailed in writing anywhere. Instead, there are important elements of the T&P process that typically rely on institutional knowledge and guidance that is often communicated informally. Junior faculty who have limited access to “informal communications” are at a significant disadvantage when they go through the T&P process even when they show accomplishments in teaching effectiveness, research, and service. The problem is especially important for women and underrepresented minority faculty in STEM disciplines that are less well represented among senior faculty in STEM. Senior faculty often serve as informal or formal mentors to their less seasoned colleagues. The goal of this article is to help demystify the T&P process by offering practical suggestions and describing some of the specific materials and steps that are an important part of documenting the development of a faculty member at a PUI.