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1.
J Environ Qual ; 48(5): 1133-1144, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589705

RESUMO

Insight into the role of phosphorus (P) in soil fertility and crop nutrition at Rothamsted, UK, and its involvement in associated environmental issues, has come from long-term field experiments initially started by J. B. Lawes in 1843 and continued by others, together with experiments on different soils. Results from the 1940s confirmed that residues of P applied in fertilizers and manures build up reserves of P in soil. There is a strong relationship between crop yield and plant-available P (Olsen P), and a critical level of Olsen P can be determined. For soils near the critical level, P-use efficiency is high when the P applied and offtake by the crop is nearly equal. Soil inorganic P is associated with various soil components and is held there with a range of bonding energies so that when no P is applied, the decline in Olsen P follows a smooth curve. We conceptualize inorganic soil P as being in four pools of vastly varying size, availability for uptake, and extractability by reagents used in routine soil analysis, and with reversible transfer of P between pools. For very disparate soils at Rothamsted and in the United States, there is a strong relationship between the change in Olsen P and P removal/input ratios, suggesting an underlying similarity in inorganic P behavior. Maintaining soil near the critical level should optimize yield and the use of the global P resource while minimizing the risk of transfer of large amounts of P to the aquatic environment.


Assuntos
Agricultura , Fósforo , Fertilizantes , Solo , Reino Unido
2.
J Environ Qual ; 48(5): 1300-1313, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589737

RESUMO

The development of highly concentrated phosphorus (P) fertilizers, such as triple superphosphate, by the Tennessee Valley Authority helped mark the beginning of a revolution in the way we manage food crop nutrition. Since then, scientists, with the help of farmers, have made great advancements in the understanding of P fate and transport across many environments but largely have failed to produce a new generation of products and/or application techniques that are widely accepted and that vastly improve plant acquisition efficiency. Under certain conditions, important advancements have been made. For example, applying liquid formulations of phosphates in lieu of dry granules in some highly calcareous soils has dramatically reduced precipitation as sparingly soluble calcium phosphate minerals, but other attempts, such as the co-application of humic substances, sorption to layered double hydroxides, or use of nanoparticles, have not generated the kind of results necessary to continue economically increasing crop yields without further environmental cost. New sources of fertility will need to be affordable to produce, transport, and furnish P to soil solution in a manner well synchronized with crop demand. This paper provides a review of recent literature on cutting-edge phosphorus fertilizer technology. The goal is that this synthesis will be used as a starting point from which a larger discussion on responsible nutrient management and increased P use efficiency research can be built.


Assuntos
Fertilizantes , Fósforo , Fosfatos , Plantas , Solo
3.
Zhongguo Zhong Yao Za Zhi ; 44(15): 3246-3252, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31602879

RESUMO

Inula japonica was used as the research object, "3414" fertilization experiment were conducted to study the effects of nitrogen,phosphorus and potassium formula fertilizer on the growth and chemical composition content of I. japonica. The characteristics of fertilizer requirement were preliminarily revealed and the study provided fertilization guidance for artificial cultivation of I. japonica. The results showed that different nitrogen,phosphorus and potassium formula fertilizers had significant effects on plant morphology,physiological and biochemical indexes,dry matter accumulation and chemical composition content. The growth indexes and chemical components of I. japonica showed an upward trend with the increase of fertilization amount,especially the nitrogen fertilizer was the most significant. The indicators were analyzed by membership function. After comprehensive evaluation,the optimal nitrogen,phosphorus and potassium formula fertilization level was N3 P2 K2,namely high level nitrogen fertilizer,medium level phosphorus fertilizer and potassium fertilizer. I. japonica is a high fertilizer demand plant,and the rational fertilization scheme is " applying nitrogen fertilizer again and applying phosphorus and potassium fertilizer properly".


Assuntos
Fertilizantes , Inula/crescimento & desenvolvimento , Nitrogênio/química , Fósforo/química , Potássio/química , Inula/química
4.
Ying Yong Sheng Tai Xue Bao ; 30(10): 3292-3302, 2019 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-31621215

RESUMO

Rice is one of the main crops in China. Therefore, it is important to understand the current status and influencing factors of nitrogen and phosphorus losses from paddy fields in China, which would facilitate assessing the potential of chemical fertilizer reduction in different rice cultivating regions. We summarized the current knowledge on nitrogen and phosphorus losses from surface runoff in major rice cultivating areas in China, as well as their influencing factors, such as rainfall, planting pattern, cultivation techniques, fertilization management, water management strategies, etc. The total nitrogen (TN) and total phosphorus (TP) losses from runoff in six major rice cropping areas ranged from 5.09 to 21.32 and 0.70 to 3.22 kg·hm-2, respectively. The highest losses of TN and TP were the South China double rice cropping area. The TN runoff losses were the lowest in the North China single rice cropping area, while the lowest TP runoff losses occurred in plateau single and double rice cropping area of the Southwest China. The peaks of TN and TP in surface water of paddy fields were generally higher than those of the runoff water based on farmers' conventional fertilization in different rice cropping areas. The peak period of nitrogen and phosphorus losses was in a week after rice fertilization. There could be a potential of 20% reduction of nitrogen and phospho-rus for farmers' conventional fertilization compared with the optimized fertilization. Among all the factors, rainfall and fertilization management were the main ones affecting the runoff losses of nitrogen and phosphorus in paddy fields. Fertilization management and water management strategies were the mostly controllable, including reduction of fertilizers, application of new fertilizers, replacement of chemical fertilizers by organic fertilizers, water-saving irrigation, etc. Overall, the risk of nitrogen and phosphorus losses in paddy fields was more prominent in the Southern China than in any other areas of China. Rice cultivation should be carried out in a more resource-efficient way to reduce nutrient loss. Future research should focus on non-point source pollution monitoring of paddy fields, nitrogen and phosphorus losses risk assessment, nitrogen and phosphorus losses characteristics and mechanisms, and new technologies for reducing chemical fertilization inputs and environmental risks.


Assuntos
Oryza , Fósforo , Agricultura , China , Monitoramento Ambiental , Fertilizantes , Nitrogênio
5.
J Environ Qual ; 48(4): 1006-1015, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31589671

RESUMO

There is an incentive for dairy farmers to maximize crop production while minimizing costs and environmental impacts. In cold climates, farmers have limited opportunity to balance field activities and manure storage requirements while limiting nutrient losses. A revised DeNitrification DeComposition (DNDC) model for simulating tile drainage was used to investigate fertilizer scenarios when applying dairy slurry or urea on silage corn ( L.) to examine N losses over a multidecadal horizon at locations in eastern Canada and the US Midwest. Management scenarios included timing (spring, fall, split, and sidedress) and method of application (injected [10 cm], incorporated [5 cm], and broadcast). Reactive N losses (NO from drainage and runoff, NO, and NH) were greatest from broadcast, followed by incorporated and then injected applications. Among the fertilizer timing scenarios, fall manure application resulted in the greatest N loss, primarily due to increased N leaching in non-growing-season periods, with 58% more N loss per metric ton of silage than spring application. Split and sidedress mineral fertilizer had the lowest N losses, with average reductions of 9.5 and 4.9%, respectively, relative to a single application. Split application mitigated losses more so than sidedress by reducing the soil pH shift due to urea hydrolysis and NH volatilization during the warmer June period. This assessment helps to distinguish which fertilizer practices are more effective in reducing N loss over a long-term time horizon. Reactive N loss is ranked across 18 fertilizer management practices, which could assist farmers in weighing the tradeoffs between field trafficability, manure storage capacity, and expected N loss.


Assuntos
Fertilizantes , Silagem , Agricultura , Canadá , Esterco , Nitrogênio , Zea mays
6.
J Environ Qual ; 48(4): 1016-1028, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31589678

RESUMO

Effective management of dairy manure is important to minimize N losses from cropping systems, maximize profitability, and enhance environmental sustainability. The objectives of this study were (i) to calibrate and validate the DeNitrification-DeComposition (DNDC) model using measurements of silage corn ( L.) biomass, N uptake, soil temperature, tile drain flow, NO leaching, NO emissions, and soil mineral N in eastern Canada, and (ii) to investigate the long-term impacts of manure management under climate variability. The treatments investigated included a zero-fertilizer control, inorganic fertilizer, and dairy manure amendments (raw and digested). The DNDC model overall demonstrated statistically "good" performance when simulating silage corn yield and N uptake based on normalized RMSE (nRMSE) < 10%, index of agreement () > 0.9, and Nash-Sutcliffe efficiency (NSE) > 0.5. In addition, DNDC, with its inclusion of a tile drainage mechanism, demonstrated "good" predictions for cumulative drainage (nRMSE < 20%, > 0.8, and NSE > 0.5). The model did, however, underestimate daily drainage flux during spring thaw for both organic and inorganic amendments. This was attributed to an underestimation of soil temperature and soil water under frequent soil freezing and thawing during the 2013-2014 overwinter period. Long-term simulations under climate variability indicated that spring applied manure resulted in less NO leaching and NO emissions than fall application when manure rates were managed based on crop N requirements. Overall, this study helped highlight the challenges in discerning the short-term climate interactions on fertilizer-induced N losses compared with the long-term dynamics under climate variability.


Assuntos
Fertilizantes , Zea mays , Agricultura , Canadá , Esterco , Nitrogênio , Silagem , Solo , Água
7.
J Environ Qual ; 48(4): 988-994, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31589683

RESUMO

Successful N management practices for the US Midwest must optimize crop production and minimize NO-N losses from subsurface tile drainage. The objective of this study was to measure the effects of N rate, N application timing, and nitrapyrin [2-chloro-6-(trichlormethyl) pyridine] on corn ( L.) production and NO-N in tile drainage water in a corn-soybean [ (L.) Merr.] rotation in Minnesota. Anhydrous ammonia was applied at 90 and 179 kg ha with nitrapyrin in the fall and at 134 kg ha with and without nitrapyrin in fall and spring. However, drainage water monitoring was only conducted on fall treatments. Over a 5-yr period, 71% of drainage occurred in April through June and <1% occurred from November through March due to frozen soil. Averaged across N treatments and crops, annual drainage ranged from 69 to 380 mm among years. From 2001 through 2003, NO-N concentrations averaged 13.8, 15.6, and 20.0 mg L in corn and 7.3, 8.2, and 12.6 mg L in soybean when 90, 134, and 179 kg N ha was fall applied with nitrapyrin to corn, respectively. Corn grain yields were greater with spring-applied N at 134 kg ha (11.3 Mg ha) than with fall-applied N at 134 and 179 kg ha with nitrapyrin (10.5 and 10.8 Mg ha, respectively), and nitrapyrin did not affect corn production or water quality. Fall application of N is common on cold soils in Minnesota. These data showed that fall application required a greater rate of N to optimize yield than spring and that greater fall rate often increased NO-N concentration and load in tile drainage water.


Assuntos
Soja , Zea mays , Agricultura , Fertilizantes , Minnesota , Nitratos , Nitrogênio , Picolinas , Rotação , Solo
8.
J Environ Qual ; 48(5): 1414-1426, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589701

RESUMO

Controlling nitrogen (N) losses from pig slurry (PS) is a challenge under no-till because amendments are left on the soil surface. We investigated the potential of shallow injection of PS, with and without addition of the nitrification inhibitor dicyandiamide (DCD), to abate gaseous ammonia (NH) and nitrous oxide (NO) emissions in winter crops in subtropical soils. Injection was compared with surface broadcasting of PS, with and without DCD. The significance of winter season on annual NO emissions was assessed. Injecting PS reduced NH volatilization compared with surface application. However, this reduction was partly offset because NO emissions increased by 77% (+1.53 kg NO-N ha) when PS was injected. Adding DCD to injected PS reduced NO emission below levels of surface-broadcast PS without the inhibitor, indicating that DCD may be a management option when injecting PS. Compared with a reference urea treatment, PS without DCD increased cumulative NO emissions 5.7-fold (from 613 to 3515 g NO-N ha) when injected, and 3.2-fold (from 613 to 1980 g NO-N ha) when surface applied. Adding DCD significantly reduced emissions with injected PS, whereas reduction was not always significant with surface-applied PS. Nitrous oxide emissions during the winter cropping season contributed 30 to 44% of annual emissions, indicating that controlling gaseous N losses in that season is required to reduce the environmental footprint of the whole cropping system. Overall, combining PS injection with DCD was an efficient practice for reducing winter-season gaseous N losses from no-till soils under subtropical climate.


Assuntos
Nitrificação , Nitrogênio , Animais , Fertilizantes , Gases , Óxido Nitroso , Estações do Ano , Solo , Suínos
9.
J Environ Qual ; 48(5): 1534-1542, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589710

RESUMO

Calcium superphosphate and apple ( Mill.) waste can be used for controlling N loss and improving compost quality during composting, whereas integrated addition of the two additives on composting process remains unexplored. Therefore, this study was conducted to investigate the effects of combined use of calcium superphosphate and apple waste on NH and NO emissions and compost quality during pig manure and wheat ( L.) straw composting. Mixtures of pig manure and wheat straw were combined with 6% phosphate fertilizer (PF), 15% apple waste (AW), 3% phosphate fertilizer + 7.5% apple waste (PA1), or 1.8% phosphate fertilizer + 10.5% apple waste (PA2) based on dry weight of the initial mixtures; a treatment with no additives served as a control (CK). The PF treatment took 3 d longer to reach thermophilic phase than the CK, PA1, and PA2 treatments. The treatments of PF and PA1 reduced NH and NO emissions by 67 and 45%, respectively. Moreover, N loss in PF and PA1 treatments (31.8 and 30.1%, respectively) was significantly less than in the CK. A pot experiment showed that application of the compost with PA1 treatment could increase plant height and dried biomass of Chinese pakchoi ( L. ssp.). We recommend adding 3% phosphate fertilizer and 7.5% apple waste to pig manure during composting.


Assuntos
Compostagem , Malus , Animais , Fertilizantes , Esterco , Nitrogênio , Fosfatos , Solo , Suínos
10.
J Environ Qual ; 48(5): 1498-1506, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589711

RESUMO

Recent evidence suggests an upward trend in surface water phosphorus (P) concentrations in many segments of Florida, including the upper basin of the St. Johns River, a region that currently receives about two-thirds of the state Class B biosolids land application. Concerns about water quality in this area are encouraging reexamination of the regulations governing biosolids programs. The objectives of this study were (i) to identify and thoroughly characterize the main biosolids sources routinely applied in the region, and (ii) to evaluate runoff and leachate N and P losses from a typical Florida Spodosol amended with biosolids or commercial inorganic fertilizer. Biosolids and inorganic fertilizer were surface applied uniformly at a rate equivalent to ∼114 kg P ha, which corresponded to a typical P load associated with nitrogen (N)-based biosolids application. Soluble reactive P (SRP) was the predominant form of P lost in runoff and leachate. Inorganic P fertilizer increased flow-weighted runoff total P concentrations nearly 60-fold relative to control treatment (0.4 vs. 22 mg P L for control and fertilizer treatments, respectively). With exception of biological P removal (BPR) biosolids, all other tested biosolids yielded flow-weighted runoff P concentrations similar to untreated soils. Cumulative P and N losses (as a percentage of P and N applied) were greater from commercial inorganic fertilizer (∼38% of P and 46% of N) than any biosolids source (3% of P and 6% of N). Results demonstrate the value of water-extractable P (WEP) as an indicator of biosolids P loss potential.


Assuntos
Fertilizantes , Fósforo , Florida , Nitrogênio , Poaceae , Solo
11.
J Environ Qual ; 48(5): 1247-1264, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589712

RESUMO

Soil phosphorus (P) cycling in agroecosystems is highly complex, with many chemical, physical, and biological processes affecting the availability of P to plants. Traditionally, P fertilizer recommendations have been made using an insurance-based approach, which has resulted in the accumulation of P in many intensively managed agricultural soils worldwide and contributed to the widespread water quality issue of eutrophication. To mitigate further environmental degradation and because future P fertilizer supplies are threatened due to finite phosphate rock resources and associated geopolitical and quality issues, there is an immediate need to increase P use efficiency (PUE) in agroecosystems. Through cultivar selection and improved cropping system design, contemporary research suggests that sufficient crop yields could be maintained at reduced soil test P (STP) concentrations. In addition, more efficient P cycling at the field scale can be achieved through agroecosystem management that increases soil organic matter and organic P mineralization and optimizes arbuscular mycorrhizal fungi (AMF) symbioses. This review paper provides a perspective on how agriculture has the potential to utilize plant and microbial traits to improve PUE at the field scale and accordingly, maintain crop yields at lower STP concentrations. It also links with the need to tighten the P cycle at the regional scale, including a discussion of P recovery and recycling technologies, with a particular focus on the use of struvite as a recycled P fertilizer. Guidance on directions for future research is provided.


Assuntos
Agricultura , Fósforo , Fertilizantes , Solo , Microbiologia do Solo
12.
J Environ Qual ; 48(5): 1145-1155, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589713

RESUMO

With more than 40 countries currently proposing to boost their national bioeconomies, there is no better time for a clarion call for a "new" bioeconomy, which, at its core, tackles the current disparities and inequalities in phosphorus (P) availability. Existing biofuel production systems have widened P inequalities and contributed to a linear P economy, impairing water quality and accelerating dependence on P fertilizers manufactured from finite nonrenewable phosphate rock reserves. Here, we explore how the emerging bioeconomy in novel, value-added, bio-based products offers opportunities to rethink our stewardship of P. Development of integrated value chains of new bio-based products offers opportunities for codevelopment of "P refineries" to recover P fertilizer products from organic wastes. Advances in material sciences are exploiting unique semiconductor and opto-electrical properties of new "two-dimensional" (2D) P allotropes (2D black phosphorus and blue phosphorus). These novel P materials offer the tantalizing prospect of step-change innovations in renewable energy production and storage, in biomedical applications, and in biomimetic processes, including artificial photosynthesis. They also offer a possible antidote to the P paradox that our agricultural production systems have engineered us into, as well as the potential to expand the future role of P in securing sustainability across both agroecological and technological domains of the bioeconomy. However, a myriad of social, technological, and commercialization hurdles remains to be crossed before such an advanced circular P bioeconomy can be realized. The emerging bioeconomy is just one piece of a much larger puzzle of how to achieve more sustainable and circular horizons in our future use of P.


Assuntos
Biotecnologia , Fósforo , Agricultura , Biocombustíveis , Fertilizantes
13.
J Environ Qual ; 48(5): 1265-1280, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589717

RESUMO

The discovery and development of phosphorus (P) and P fertilizers provide context for current management conventions. Average crop yields were stagnant before the Green Revolution but have steadily increased since. This, along with conventional P management, has resulted in widely depleting soil P levels. Improved technology and management are needed to meet the increasing P demand. Modern hybrids and cultivars have different P demand and uptake patterns that require changes in conventional P fertilizer placement and timing. Phosphorus fertilizer recommendations based on soil analysis remains valid, but evidence suggests a need for recalibrating soil test P (STP) critical levels (the STP concentration at which a response to P fertilizer would not be expected) and P fertilizer rates to accommodate high-yield scenarios. Considering higher P fertilizer rates as a single solution poses environmental challenges, highlighting the need for improved P use efficiency (PUE). Phosphorus fertilization approaches that have the potential to improve PUE and enable high yields include crop-specific precision placement of P, informed timing of P fertilizers, and new enhanced efficiency sources of P fertilizer. This paper examines these management approaches from historical, production, and environmental perspectives in modern cropping systems.


Assuntos
Agricultura , Fósforo , Fertilizantes , Modelos Teóricos , Solo
14.
J Environ Qual ; 48(5): 1444-1453, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589718

RESUMO

Corn ( L.) production in poorly drained claypan soils in the US Midwest is a challenge due to low soil permeability, which may result in wetter soil conditions and relatively large amounts of soil NO emissions early in the growing season. The objectives of this study were to determine the effects of urea fertilizer placement with and without nitrapyrin (NI) on daily and cumulative soil NO emissions, and yield-scaled NO emissions in 2016 and 2017. Treatments included urea deep banded to a 20-cm depth (DB), urea deep banded to 20 cm plus NI (DB+NI), urea incorporated after a surface broadcast application to ∼8-cm depth (IA), urea broadcast on the soil surface (SA), and a nonfertilized control (NTC). Fertilizer was applied at 202 kg N ha. Surface soil NO efflux rates were generally lower (<50 g NO-N ha d) during the first 3 wk after N fertilization and latter parts of the growing seasons. When averaged across the 2016 and 2017 growing seasons, all fertilized treatments had significantly greater (2.33-5.60 kg NO-N ha, < 0.05) cumulative soil NO emissions than NTC. The DB+NI treatment had 54 and 55% lower cumulative soil NO emissions than IA and SA, respectively. In 2017, DB+NI had similar soil yield-scaled NO emissions to NTC. Percentage grain yield increase over NTC was highest for DB and DB+NI. Grain yield in 2016 was 14 to 18% higher for DB and DB+NI than SA. Results suggest that DB+NI is an effective management strategy for reducing cumulative soil NO emissions and increasing grain yields over the growing season.


Assuntos
Óxido Nitroso , Solo , Fertilizantes , Picolinas , Ureia
15.
J Environ Qual ; 48(5): 1167-1175, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589723

RESUMO

In the last decade, crop production in China has dramatically improved due to greater phosphorus (P) input. As P fertilizer application rates increased from 88 to 123 kg PO ha yr during 2004 to 2014, total P use efficiency (total P output in crops as a percentage of total P input) dropped from 68 to 20%, leading to an accumulation of >90 kg PO ha in the soil each year. Phosphorus lost from agriculture is the second greatest contributor to waterbody eutrophication in China, accounting for 25% of total P losses in 2010; the main contributor is livestock husbandry. Given these problems, as well as the finite nature of P reserves, three strategies are proposed here to reduce P fertilizer application rates, improve P use efficiency, and minimize the environmental risk caused by P loss in China: (i) improving soil legacy P utilization by modifying cropping systems, rhizosphere management, or microbial engineering, (ii) increasing P use efficiency by reducing P fertilizer applications and minimizing P fertilizer fixation, and (iii) promoting the extension of soil P management strategies. For these management strategies to succeed in China, close cooperation should be established among farmers, scientists, and governments in the future.


Assuntos
Fertilizantes , Solo , Agricultura , Animais , China , Fósforo
16.
J Environ Qual ; 48(5): 1281-1294, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589725

RESUMO

The use of phosphorus (P) fertilizers in arable crop and pastoral systems is expected to change as modern agriculture is challenged to produce more food with fewer inputs. Agricultural systems models offer a dual purpose to support and integrate recent scientific advances and to identify strategies for farmers to improve nutrient efficiency. However, compared with nitrogen and carbon, advances in P modeling have been less successful. We assessed the potential opportunity of P modeling to increase P efficiency for modern agriculture and identified the current challenges associated with modeling P dynamics at the field scale. Three major constraints were (i) a paucity of detailed field datasets to model strategies aimed at increasing P use efficiency, (ii) a limited ability to predict P cycling and availability under the local effects of climate change, and (iii) a restricted ability to match measured soil P fractions to conceptual and modelable pools in soils with different mineral properties. To improve P modeling success, modelers will need to walk a tightrope to balance the roles of assisting detailed empirical research and providing practical land management solutions. We conclude that a framework for interdisciplinary collaboration is needed to acquire suitable datasets, continually assess the need for model adjustment, and provide flexibility for progression of scientific theory. Such an approach is likely to advance P management for increased P use efficiency.


Assuntos
Fósforo , Solo , Agricultura , Produtos Agrícolas , Fertilizantes
17.
J Environ Qual ; 48(5): 1356-1369, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589727

RESUMO

Phosphorus (P) fertilizer has played a vital role in increasing the productivity of crop production in the northern Great Plains for approximately 100 years. Throughout this period, agricultural production practices have changed dramatically, while our knowledge of P behavior and beneficial management practices has improved. Some of the more recent and substantial changes in farming practices on the northern Great Plains include widespread adoption of reduced tillage systems, introduction of new crops and high-yielding cultivars, intensification and extension of crop rotations, development of new fertilizer products, increased appreciation of the role of microbial interactions in P dynamics, and growing concern for the effects of P on water quality. As cropping systems, technology, and societal demands evolve over time, nutrient management practices must also evolve to address concerns and take advantage of emerging opportunities. Classic principles and new P fertilizer technologies and management practices must be integrated into packages of 4R practices that optimize crop yield and agronomic efficiency while minimizing negative environmental impact and conserving P resources. Although a wide range of products and practices can be combined for this approach, placing ammonium phosphate fertilizer in a band, in or near the seed-row, at the time of seeding and at a rate that matches P removal by the crop generally provides the greatest P efficiency, long-term sustainability, and environmental protection for small grain, oilseed, and pulse crop production in the northern Great Plains.


Assuntos
Fertilizantes , Fósforo , Agricultura , Conservação dos Recursos Naturais , Produtos Agrícolas
18.
J Environ Qual ; 48(5): 1543-1548, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589732

RESUMO

Agricultural runoff is an important contributor to water quality impairment. This study was conducted to evaluate the potential role of field-scale management on carbon (C), nitrogen (N), and phosphorus (P) stoichiometry in soils and runoff from agricultural fields. Cultivated and pasture fields at the Riesel watersheds in central Texas were used for this analysis, and nutrients were transformed to evaluate relative to the Redfield ratio (106 C/16 N/1 P). Using the Redfield ratio, all soil samples were P depleted relative to C and N. The majority of stormflow and baseflow runoff samples contained 9 to 19% Redfield N relative to C and P. Shifting from inorganic fertilizer application to poultry litter as a fertilizer source resulted in increased absolute C, N, and P concentrations in stormflow and baseflow runoff. Increasing rates of poultry litter application increased the Redfield P relative to Redfield C, whereas Redfield N remained relatively constant at roughly 9 to 11% in stormflow runoff from cultivated fields. This study shows how land use and management can affect C/N/P stoichiometry in stormflow and baseflow runoff.


Assuntos
Esterco , Solo , Animais , Fertilizantes , Fósforo , Aves Domésticas , Texas , Movimentos da Água
19.
J Environ Qual ; 48(5): 1295-1299, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589734

RESUMO

When phosphorus (P) fertilizers were introduced, the main goals were to increase the productivity and profitability of agricultural crop production. Over time, other goals have been added: to minimize losses affecting water quality, to increase recycling, to reduce consumption of the limited resource, to improve soil health, and to enhance biodiversity. The science of 4R nutrient stewardship addresses these multiple goals. Across latitudes, temperate and tropical soils differ in their chemical reactivity with P. Legacies of cumulative P surplus, however, differ more widely across longitudes than latitudes. As of 2016, the ratio of cumulative P surplus to current crop P removal ranged from 18 in the United States to 31 in Brazil to 63 in western Europe. The opportunity to use these legacies to improve P use efficiency-and to reduce risk of harm to water quality-in all three regions depends on the improvement of tools to assess the availability of soil P to crops. Science focused on balanced crop nutrition and systematic analysis of crop response has the opportunity to improve farm-level tools to guide responsible management of P. Transitions in 4R practice depend on engagement between science and industry not only at the farm level but along the full agricultural value chain. Whole-system changes may be necessary to enable practitioners to implement 4R nutrient stewardship strategies that can in turn result in major improvements to full-chain use efficiency of the earth's P resources.


Assuntos
Nutrientes , Fósforo , Agricultura , Brasil , Fertilizantes , Solo
20.
J Environ Qual ; 48(5): 1156-1166, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589738

RESUMO

Adequate phosphorus (P) is needed for crop production, but excessive P poses a potential risk to water quality. Results from the cumulative P balance calculations within the indicator of risk of water contamination by phosphorus (IROWC-P) developed in Canada were assessed to determine the spatial and temporal trends in P accumulation at a regional scale and to consider the implications of these trends. Regional cumulative P balances were calculated from census data as a proxy for soil test P (STP) values, including the contribution of fertilizer or manure P to these balances. Ideally, over time we would see a convergence of soil test values at the low end of the critical response range for crop growth, where agronomic and environmental considerations are balanced, but this does not appear to be the case for many regions in Canada. Nationally, about 61% of agricultural land was predicted to be low in STP, and over half of this land is failing to replace the P that is removed each year. While only about 10% of the agricultural land has accumulated significantly more P than is needed for crop growth, almost all of this land is continuing to accumulate P rather than drawing it down. Manure is the dominant P source for continuing accumulation in regions with high or very high estimated STP; reducing this input will be difficult because of the nature of manure and the investment in buildings and infrastructure tied to specific locations, but it is clear that current Canadian policies need strengthened.


Assuntos
Fósforo , Solo , Agricultura , Canadá , Fertilizantes , Esterco
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