Leaching Losses Of Phosphorus Research Articles

Quantifying Phosphorus Leaching Loss from Mollisol with Organic Amendments

The phosphorus (P) leaching from continuous fertilization is generally neglected in mollisol. The in situ leaching loss of phosphorus (P), especially dissolved organic P, is poorly quantified under organic amendments given its potential environmental risks. In this study, we conducted an in situ soil column experiment, instead of the traditional measuring of the soil layer, in the mollisol area of northeast China to investigate the seasonal variations in different P forms under three typical fertilization practices, including chemical fertilizer (CF), CF supplemented with straw (CFS), and CF co-applied with straw and manure (CFSM). Compared with the CF treatment, CFS treatment generally reduced the leaching loss of dissolved organic P by 57.3% to reduce the total P loss, while the CFSM treatment increased the leaching loss of dissolved inorganic P by 20.9% to increase the total P loss. Other than the effects of management practices, precipitation and temperature-oriented environmental factors significantly affected the seasonal variation in leaching loss of both the dissolved and particulate P forms. We conclude that straw incorporation into the mollisol of northeast China is recommended, considering its low leaching risk of P, while a co-amendment of straw and manure resulted in the opposite. Despite the slight environmental risk of P leaching loss (0.75–1.95% of external P input per year) practically quantified by in situ experiments, a proper reduction in chemical P input with organic amendments may be an effective P fertilizer management strategy in mollisol areas.

Influence of soil test phosphorus level and leaching volume on phosphorus leaching

Phosphorus (P) is an essential nutrient in agricultural production, yet its losses contribute to eutrophication in freshwater systems. To mitigate this, there is increasing interest in quantifying soluble P leaching losses and including them in P indices. The objectives of this research were to 1) evaluate water soluble P leaching loss from topsoils (0-15 cm) across a range of initial soil test P (STP) levels; 2) determine the effects of soil type, physiochemical soil properties, and leaching volume on P leaching loss; and 3) determine the predictability of P leaching losses from soil tests. Intact soil cores (3.81 cm in diameter, 0–15 cm deep) were collected from six agricultural fields in Minnesota and leached with deionized water offsite. Additional columns were collected to identify the influence of three leaching volumes on P leaching load. Phosphorus leaching loss was impacted by soil type, initial STP level, and the volume of the leaching event. Leachate P concentration increased with increasing STP level and remained consistent among leaching volumes. Concentrations were not diluted with increased leaching volumes. Consequently, leaching volume was the primary driver of total P load. Several linear and machine learning models were employed to predict P leachate concentration. Phosphorus concentration was best predicted using a Ridge Regression model using two soil tests: the degree of phosphorus sorption (DPSOP) and water extractable P (WEP) (R2 = 0.58, RMSE = 0.06). The model prediction of P leaching loss is promising, although further research on subsoil interactions is needed. This article is protected by copyright. All rights reserved

Phosphorus Leaching Loss from Mollisol with Organic Amendments

Phosphorus Leaching Loss from Mollisol with Organic Amendments

Changes in nutrient balance, environmental effects, and green development after returning farmland to forests: A case study in Ningxia, China

Returning sloping farmland (>25°) to forest/grassland (RFTF) is an effective ecological measure for soil and water conservation. However, changes in nutrient cycles and green development are still unclear. Ningxia, in Northwestern China, began to implement RFTF in 2000. Here, we used the NUFER model to calculate the input and loss of nitrogen and phosphorus, utilization efficiency, production and consumption at food-chain scale in Ningxia for the period 1985–2015. Five aspects comprised the evaluation of green development: society, economy, resources, environment, and productivity. Results showed that forest coverage rate increased from 7.74% to 33.2%, while cropping area decreased by 6.6%. NH3 loss increased from 53,000 to 83,000 tons (56%), N2O increased from 1200 to 2300 tons (92%) and leaching loss from 18,000 to 62,000 tons (240%). Phosphorus leaching loss increased from 13,000 to 35,000 tons (130%). The environmental cost of food nitrogen per unit of production decreased from 8 to 6.7 kg/kg (19.4%). Nitrogen and phosphorus use efficiencies decreased by 4.8% and 58% in crops-animal systems, respectively, but increased by 652% and 430% in animal husbandry systems. The proportion of animal protein production increased from 18.3% to 39.0% (113%). The major source of organic waste was livestock and poultry manure and urine (70%). Indicators for achieving green development level increased from 14 to 18 (14.7%). Improving the level of scientific and technological management of aquaculture system, increasing the proportion of organic matter returned to farmlands, and paying attention to the combination of planting and breeding will effectively promote future cycling efficiency of nitrogen and phosphorus in the food chain, and the sustainability of agriculture towards green development.

Effect of Biochar and Coal Fly Ash Soil Amendments on the Leaching Loss of Phosphorus in Subtropical Sandy Ultisols

Leaching of phosphorus fertilizer from loose-structured subtropical soils is a major course of agricultural water pollution in southeastern USA. Soil amendments play a major role in the phosphorus retention in soil through different mechanisms. In the present study we tested the effect of two soil amendments; biochar and coal fly ash in immobilizing the soluble phosphorus fertilizer added to sandy Ultisol soils from subtropical USA. Column leaching tests were conducted with Ultisol soil added with biochar (from avocado branch cut biomass) and coal fly ash at 5 tons/ha rate, under simulated rainfall, to collect the leachate over five pore volumes. The leachate was analyzed for the phosphate phosphorus content. In the end, the soil columns were carefully extracted, sectioned and analyzed for the total phosphorus, after acid digestion. Results showed 50% and 6% drop of soluble phosphorus leaching loss in biochar and coal fly ash added soil respectively. Soil amendments have shifted the loosely bound phosphorus into the Ca/Mg bound and Al/Fe/Mn bound pools which are not readily water extractable. Addition of biochar and coal fly ash together showed a synergistic interaction effect in reducing the leaching loss of phosphorus which needs further investigation to understand the exact mechanism.

Adsorption Behaviors and Removal Efficiencies of Inorganic, Polymeric and Organic Phosphates from Aqueous Solution on Biochar Derived from Sewage Sludge of Chemically Enhanced Primary Treatment Process

Adsorption behaviors and removal efficiencies of different phosphorus species on sewage sludge-based biochar (SBB) were investigated, with powder activated carbon (PAC) as a comparison. The adsorption efficiencies of potassium dihydrogen phosphate, sodium tripolyphosphate and sodium glycerol-phosphate on SBB are 81.91%–92.86%, 66.02%–90.66% and 25.48%–38.94%, when the initial pH values of phosphate solutions are 3–10, 4–10 and 3–10, respectively. The maximal adsorption capacities of phosphates on SBB are 2.1–5.3 times those of PAC. X-ray photoelectron spectroscopy analysis indicates that ligand-exchange mechanism and Lewis acid-base interactions occur between hydrolysates of surface-Fe2+/surface-Fe3+ and phosphates, and the precipitates of phosphates accumulate on the surface of SBB and separate from the aqueous solution. These results demonstrate that SBB is an effective adsorbent for phosphorus removal and recovery in wastewater, and it also has the potential to reduce phosphorus leaching loss in the soil when applied in soil amendment.

Impact of Fertilization and Soil Phosphorus Status on Phosphorus Leaching from Soil in Vegetable Greenhouse

The vegetable utilization rate of phosphorus fertilizer in greenhouse condition was low in the season of fertilizer application, resulting in phosphorus accumulation in the top soil year after year. The risk of phosphorus loss through leaching increased under the circumstance of inappropriate watering management and fertilization. In this study, leaching experiments using columns packed with a greenhouse soil with different soil phosphorus status (low, medium and high levels) were carried out under greenhouse condition to investigate the impact of fertilizer application on phosphorus leaching from greenhouse soil. The fertilization treatments included no fertilizer [CK], organic manure and chemical fertilizer [M+NPK], organic manure [M], chemical fertilizer [NPK]. The vertical migration and leaching loss of soil phosphorus were measured. Results were as follows: (1) total phosphorus (TP) content increased with the extension of leaching time. In the low-level- and medium-level-phosphorus greenhouse soils, TP concentration in the effluent increased with the application of manure; (2) In the high-level-phosphorus greenhouse soil, phosphorus in the effluent from the treatment with the use of fertilizer was the highest TP, with accumulative leaching amount of 2.85 mg in 51 days. The leaching of phosphorus became small after 36 days of leaching experiment. Our study showed that application of manure and chemical fertilizer at proper rates according to soil phosphorus status is beneficial to reduce the leaching loss of phosphorus to the environment.

Phosphorus Status and Risk of Phosphate Leaching Loss From Vegetable Soils of Different Planting Years in Suburbs of Changsha, China

The aim of the study was to develop an index to assess the environmental risk of P loss potential in vegetable soils with chronic difference of plantation in the suburbs of Changsha, Hunan Province, China. Chemical methodology was used to study soil phosphorus status and the relationships between available P in soil and potential soil leaching P. The results showed that there was a significant linear relationship between Olsen P and CaCl 2-P or P concentration in soil solution. Olsen P increased sharply when either CaCl 2-P or P concentration in soil solution reached a certain level. It was confirmed that 80 mg kg −1 of Olsen P was the critical value of soil P leaching in the vegetable soils. P leaching probability over the critical was assessed by GIS and indicator Kriging and four secondary risks of phosphorus leaching loss were defined. In the area with vegetable cropping for over 30 yr (Chenjiadu) and 10–15 planting years (Huangxingzhen), the indices of phosphorus leaching loss risk were 3 and 2.93, respectively. These two areas belonged to strong secondary of risk of phosphate leaching loss. In the new vegetable planting field less than 2 yr (Ningxiang), the index was 0.06, which had almost no risk of phosphorus leaching. In vegetable soils in the suburban region of Changsha, the phosphorus leaching peotential is high and the phosphorus leaching loss is related to chronic length of vegetable cropping.

Effect of fertilization and irrigation schedule on water and fertilizer solute transport for wheat crop in a sub-humid sub-tropical region

In order to increase the water and fertilizer use efficiency and decrease the losses of water and fertilizer solutes (N and P), it is necessary to assess the influence of level of fertilization and irrigation schedule on movement and balance of water and fertilizers in the root zone. With this goal, the reported study was undertaken to determine the effect of fertilization and irrigation schedule on water movement and fertilizer solute transport in wheat crop field in a sub-tropical sub-humid region. Field experiments were conducted on wheat crop of cultivar Sonalika ( Triticum aestivum L.) during the years 2002–2003, 2003–2004 and 2004–2005. Each experiment consisted of four fertilizer treatments and three irrigation treatments during the wheat growth period. During the experiment, the irrigation treatments were: I 1 = 10% maximum allowable depletion (MAD) of available soil water (ASW); I 2 = 40% MAD of ASW; I 3 = 60% MAD of ASW. The fertilizer treatments during the experiment were: F 1 = control treatment with N:P 2O 5:K 2O as 0:0:0 kg ha −1; F 2 = fertilizer application of N:P 2O 5:K 2O as 80:40:40 kg ha −1; F 3 = fertilizer application of N:P 2O 5:K 2O as 120:60:60 kg ha −1 and F 4 = fertilizer application of N:P 2O 5:K 2O as 160:80:80 kg ha −1. The results of the investigation revealed that low volume high frequency irrigation results in higher deep percolation losses than the low frequency high volume irrigation with different levels of fertilization for wheat crop in coarse lateritic soil, whereas different levels of fertilization did not significantly affect soil water balance of the wheat crop root zone during all the irrigation schedules. Level of fertilization and irrigation schedule had significant effect on nitrogen leaching loss whereas irrigation schedules had no significant effect on nitrogen uptake under different levels of fertilization. On the other hand, the leaching loss of phosphorus was not significantly influenced by the irrigation schedule and level of fertilization of wheat crop. This indicated that PO 4–P leaching loss was very low in the soil solution as compared to nitrogen due to fixation of phosphorus in soils. From the observed data of nitrogen and phosphorus use efficiency, it was revealed that irrigation schedule with 40% maximum allowable depletion of available soil water with F 2 fertilizer treatment (N:P 2O 5:K 2O as 80:40:40 kg ha −1) was the threshold limit for wheat crop with respect to nitrogen and phosphorus use, crop yield and environmental pollution.

Use of amendments to reduce leaching loss of phosphorus and other nutrients from a sandy soil in Florida

Transport of P from agricultural land contributes to the eutrophication of surface waters. Soil amendment is considered one of the best management practices (BMPs) to reduce P loss from sandy soils. Laboratory column leaching experiments were conducted to evaluate the effectiveness of different soil amendments in reducing P leaching from a typical sandy soil in Florida. The tested amendments were CaCl2, CaCO3, Al(OH)3, cellulose, and mill mud, and applied at the rate of 15 g/kg for a single amendment and each 7.5 g/kg if two amendments were combined. Leaching was conducted every four days for 32 days, 250 mL of deionized water being leached for each column per leaching event. Leachates were collected from each leaching event and analyzed for reactive P, PO4-P, and macro and micro-elements. Except for the soils amended with CaCl2, or CaCl2+CaCO3, reactive P and PO4-P leaching losses mainly occurred in the first three leaching events. Phosphorus leaching from the soils amended with CaCl2 or CaCl2+CaCO3 was less but more persistent than that of other amendments. Reactive P leaching loss was reduced by 36.0% and 40.4% for the amendments of CaCl2, and CaCl2+CaCO3, respectively, as compared with chemical fertilizer alone, and the corresponding values for PO4-P were 70.8% and 71.9%. The concentrations of K, Mg, Cu, and Fe in leachate were also decreased by CaCl2 or CaCl2+CaCO3 amendment. Among the seven amendments, CaCl2, CaCO3, or their combination were most effective in reducing P leaching from the sandy soil, followed by cellulose and Al(OH)3, the effects of mill mud and mill mud + Al(OH)3 were marginal. These results indicate that the use of CaCl2, CaCO3, or their combination can significantly reduce P leaching from sandy soil, and should be considered in the development of BMPs for the sandy soil regions. Recommendations and Outlook. Most agricultural soils in south Florida are very sandy with minimal holding capacities for moisture and nutrients. Repeated application of fertilizer is necessary to sustain desired yield of crops on these soils. However, eutrophication of fresh water systems in this area has been increasingly concerned by the public. Losses of P from agricultural fields by means of leaching and surface runoff are suspected as one of the important non-point contamination sources. The benefits and effectiveness of soil amendment in reducing P losses from cropping production systems while sustaining desired crop yield need to be demonstrated. Calcium chloride, CaCO3, or their combination significantly reduce P leaching from sandy soil, and should be considered in the development of BMPs for the sandy soil regions.

Use of dolomite phosphate rock (DPR) fertilizers to reduce phosphorus leaching from sandy soil

There is increasing concern over P leaching from sandy soils applied with water-soluble P fertilizers. Laboratory column leaching experiments were conducted to evaluate P leaching from a typical acidic sandy soil in Florida amended with DPR fertilizers developed from dolomite phosphate rock (DPR) and N-Viro soil. Ten leaching events were carried out at an interval of 7 days, with a total leaching volume of 1183 mm equivalent to the mean annual rainfall of this region during the period of 2001–2003. Leachates were collected and analyzed for total P and inorganic P. Phosphorus in the leachate was dominantly reactive, accounting for 67.7–99.9% of total P leached. Phosphorus leaching loss mainly occurred in the first three leaching events, accounting for 62.0–98.8% of the total P leached over the whole period. The percentage of P leached (in the total P added) from the soil amended with water-soluble P fertilizer was higher than those receiving the DPR fertilizers. The former was up to 96.6%, whereas the latter ranged from 0.3% to 3.8%. These results indicate that the use of N-Viro-based DPR fertilizers can reduce P leaching from sandy soils.