Tracking fertiliser and soil nitrogen in irrigated cotton: uptake, losses and the soil N stock

Soil Research ◽  
2017 ◽  
Vol 55 (3) ◽  
pp. 264 ◽  
Author(s):  
B. C. T. Macdonald ◽  
Y. F. Chang ◽  
A. Nadelko ◽  
S. Tuomi ◽  
M. Glover

This paper explores the importance of the N loss pathways relative to the immobilisation and soil mineral N supply during a cotton season. Despite using an agronomic practice of splitting urea application to reduce losses and an optimal rate (232kg urea-N ha–1) for the experiment, the average fertiliser recovery was 32%, which indicates that soil N mineralisation is a key source of N for irrigated cotton production systems. A large amount of the fertiliser (62kgNha–1) was immobilised in the soil at the end of the season and during the season the soil supplied 159kgNha–1 to the plant via mineralisation. During the season, large N losses occurred from the field via the atmospheric, deep drainage and surface run-off pathways (143kgNha–1). The losses occurred directly after fertilisation, predominantly at the start of the season when the majority of the urea fertiliser was applied (180kg urea-N ha–1). This indicates that the form, placement and timing of the fertiliser did not synchronise with soil and crop N dynamics and irrigation practice. Over the course of the measurement season, based on the N inputs, losses and storage budget, a 42kgNha–1 soil deficit was observed. Further longer term work is required to quantify the magnitude and significance of the soil N stock across different systems.

Soil Research ◽  
2017 ◽  
Vol 55 (1) ◽  
pp. 70 ◽  
Author(s):  
B. C. T. Macdonald ◽  
A. J. Ringrose-Voase ◽  
A. J. Nadelko ◽  
M. Farrell ◽  
S. Tuomi ◽  
...  

Leaching of nitrogen (N) in intensive irrigated agriculture can be a significant loss pathway. Though many studies have focussed on losses of mineral N, and in particular nitrate, dissolved organic N (DON) has received less coverage. In the present study, over a 5-year period (2008–2013), 740kgNha–1 fertiliser was applied to an irrigated cotton–wheat–maize rotation on a cracking clay (grey Vertosol). Deep drainage from the undisturbed soil profile at the site was measured at 2.1m below the soil surface using a variable tension lysimeter. In total, 108mm of drainage occurred during the 5 years and the majority of the drainage and the irrigations occurred during the cotton seasons. The majority of the N loss occurred during the first 3–4 irrigations and neither the N loss nor its composition were affected by the product or timing of the fertiliser application. The N in the drainage was composed of 12.8kgNOx-Nha–1, 8.7 DON-N and 0.1 NH4+-Nkgha–1, which shows that DON is an important component (40%) of the deep drainage N from irrigated Vertosol cotton production systems. Overall the total N flux lost via deep drainage represents 3% of the applied N fertiliser.


1993 ◽  
Vol 28 (3-5) ◽  
pp. 691-700 ◽  
Author(s):  
J. P. Craig ◽  
R. R. Weil

In December, 1987, the states in the Chesapeake Bay region, along with the federal government, signed an agreement which called for a 40% reduction in nitrogen and phosphorus loadings to the Bay by the year 2000. To accomplish this goal, major reductions in nutrient loadings associated with agricultural management practices were deemed necessary. The objective of this study was to determine if reducing fertilizer inputs to the NT system would result in a reduction in nitrogen contamination of groundwater. In this study, groundwater, soil, and percolate samples were collected from two cropping systems. The first system was a conventional no-till (NT) grain production system with a two-year rotation of corn/winter wheat/double crop soybean. The second system, denoted low-input sustainable agriculture (LISA), produced the same crops using a winter legume and relay-cropped soybeans into standing wheat to reduce nitrogen and herbicide inputs. Nitrate-nitrogen concentrations in groundwater were significantly lower under the LISA system. Over 80% of the NT groundwater samples had NO3-N concentrations greater than 10 mgl-1, compared to only 4% for the LISA cropping system. Significantly lower soil mineral N to a depth of 180 cm was also observed. The NT soil had nearly twice as much mineral N present in the 90-180 cm portion than the LISA cropping system.


2019 ◽  
Vol 446 (1-2) ◽  
pp. 163-177 ◽  
Author(s):  
Arlete S. Barneze ◽  
Jeanette Whitaker ◽  
Niall P. McNamara ◽  
Nicholas J. Ostle

Abstract Aims Grasslands are important agricultural production systems, where ecosystem functioning is affected by land management practices. Grass-legume mixtures are commonly cultivated to increase grassland productivity while reducing the need for nitrogen (N) fertiliser. However, little is known about the effect of this increase in productivity on greenhouse gas (GHG) emissions in grass-legume mixtures. The aim of this study was to investigate interactions between the proportion of legumes in grass-legume mixtures and N-fertiliser addition on productivity and GHG emissions. We tested the hypotheses that an increase in the relative proportion of legumes would increase plant productivity and decrease GHG emissions, and the magnitude of these effects would be reduced by N-fertiliser addition. Methods This was tested in a controlled environment mesocosm experiment with one grass and one legume species grown in mixtures in different proportions, with or without N-fertiliser. The effects on N cycling processes were assessed by measurement of above- and below-ground biomass, shoot N uptake, soil physico-chemical properties and GHG emissions. Results Above-ground productivity and shoot N uptake were greater in legume-grass mixtures compared to grass or legume monocultures, in fertilised and unfertilised soils. However, we found no effect of legume proportion on N2O emissions, total soil N or mineral-N in fertilised or unfertilised soils. Conclusions This study shows that the inclusion of legumes in grass-legume mixtures positively affected productivity, however N cycle were in the short-term unaffected and mainly affected by nitrogen fertilisation. Legumes can be used in grassland management strategies to mitigate climate change by reducing crop demand for N-fertilisers.


2021 ◽  
Vol 13 (10) ◽  
pp. 5649
Author(s):  
Giovani Preza-Fontes ◽  
Junming Wang ◽  
Muhammad Umar ◽  
Meilan Qi ◽  
Kamaljit Banger ◽  
...  

Freshwater nitrogen (N) pollution is a significant sustainability concern in agriculture. In the U.S. Midwest, large precipitation events during winter and spring are a major driver of N losses. Uncertainty about the fate of applied N early in the growing season can prompt farmers to make additional N applications, increasing the risk of environmental N losses. New tools are needed to provide real-time estimates of soil inorganic N status for corn (Zea mays L.) production, especially considering projected increases in precipitation and N losses due to climate change. In this study, we describe the initial stages of developing an online tool for tracking soil N, which included, (i) implementing a network of field trials to monitor changes in soil N concentration during the winter and early growing season, (ii) calibrating and validating a process-based model for soil and crop N cycling, and (iii) developing a user-friendly and publicly available online decision support tool that could potentially assist N fertilizer management. The online tool can estimate real-time soil N availability by simulating corn growth, crop N uptake, soil organic matter mineralization, and N losses from assimilated soil data (from USDA gSSURGO soil database), hourly weather data (from National Weather Service Real-Time Mesoscale Analysis), and user-entered crop management information that is readily available for farmers. The assimilated data have a resolution of 2.5 km. Given limitations in prediction accuracy, however, we acknowledge that further work is needed to improve model performance, which is also critical for enabling adoption by potential users, such as agricultural producers, fertilizer industry, and researchers. We discuss the strengths and limitations of attempting to provide rapid and cost-effective estimates of soil N availability to support in-season N management decisions, specifically related to the need for supplemental N application. If barriers to adoption are overcome to facilitate broader use by farmers, such tools could balance the need for ensuring sufficient soil N supply while decreasing the risk of N losses, and helping increase N use efficiency, reduce pollution, and increase profits.


Author(s):  
Subin Kalu ◽  
Gboyega Nathaniel Oyekoya ◽  
Per Ambus ◽  
Priit Tammeorg ◽  
Asko Simojoki ◽  
...  

AbstractA 15N tracing pot experiment was conducted using two types of wood-based biochars: a regular biochar and a Kon-Tiki-produced nutrient-enriched biochar, at two application rates (1% and 5% (w/w)), in addition to a fertilizer only and a control treatment. Ryegrass was sown in pots, all of which except controls received 15N-labelled fertilizer as either 15NH4NO3 or NH415NO3. We quantified the effect of biochar application on soil N2O emissions, as well as the fate of fertilizer-derived ammonium (NH4+) and nitrate (NO3−) in terms of their leaching from the soil, uptake into plant biomass, and recovery in the soil. We found that application of biochars reduced soil mineral N leaching and N2O emissions. Similarly, the higher biochar application rate of 5% significantly increased aboveground ryegrass biomass yield. However, no differences in N2O emissions and ryegrass biomass yields were observed between regular and nutrient-enriched biochar treatments, although mineral N leaching tended to be lower in the nutrient-enriched biochar treatment than in the regular biochar treatment. The 15N analysis revealed that biochar application increased the plant uptake of added nitrate, but reduced the plant uptake of added ammonium compared to the fertilizer only treatment. Thus, the uptake of total N derived from added NH4NO3 fertilizer was not affected by the biochar addition, and cannot explain the increase in plant biomass in biochar treatments. Instead, the increased plant biomass at the higher biochar application rate was attributed to the enhanced uptake of N derived from soil. This suggests that the interactions between biochar and native soil organic N may be important determinants of the availability of soil N to plant growth.


Soil Research ◽  
2001 ◽  
Vol 39 (3) ◽  
pp. 519 ◽  
Author(s):  
J. Sierra ◽  
S. Fontaine ◽  
L. Desfontaines

Laboratory incubations and a field experiment were carried out to determine the factors controlling N mineralization and nitrification, and to estimate the N losses (leaching and volatilization) in a sewage-sludge-amended Oxisol. Aerobically digested sludge was applied at a rate equivalent to 625 kg N/ha. The incubations were conducted as a factorial experiment of temperature (20˚C, 30˚C, and 40˚C) soil water (–30 kPa and –1500 kPa) sludge type [fresh (FS) water content 6230 g/kg; dry (DS) water content 50 g/kg]. The amount of nitrifiers was determined at the beginning and at the end of the experiment. The incubation lasted 24 weeks. The field study was conducted using bare microplots (4 m) and consisted of a factorial experiment of sludge type (FS and DS) sludge placement (subsurface, I+; surface, I–). Ammonia volatilization and the profile (0–0.90 m) of mineral N concentration were measured during 6 and 29 weeks after sludge application, respectively. After 24 weeks of incubation at 40˚C and –30 kPa, net N mineralization represented 52% (FS) and 71% (DS) of the applied N. The difference between sludges was due to an initial period of N immobilization in FS. Nitrification was more sensitive than N mineralization to changes in water potential and it was fully inhibited at –1500 kPa. The introduction of a large amount of nitrifiers with FS did not modify the rate of nitrification, which was principally limited by soil acidity (pH 4.9). Although N mineralization was greatest at 30˚C, nitrification increased continuously with temperature. Nitrogen mineralization from DS was well described by the double-exponential equation. For FS, the equation was modified to take into account an immobilization-remineralization period. Sludge placement significantly affected the soil NO-3/NH+4 ratio in the field: 16 for I+ and 1.5 for I–, after 11 weeks. In the I– treatment, nitrification of the released NH+4 was limited by soil moisture because of the dry soil mulch formed a few hours after rain. At the end of the field experiment, the estimated losses of N by leaching were 432 kg N/ha for I+ and 356 kg N/ha for I–. Volatilization was not detectable in the I+ microplots and it represented only 0.5% of the applied N in the I– microplots. The results showed that placement of sludge may be a valuable tool to decrease NO-3 leaching by placing the sludge under unfavourable conditions for nitrification.


2008 ◽  
Vol 100 (1) ◽  
pp. 42-51 ◽  
Author(s):  
P. Jost ◽  
D. Shurley ◽  
S. Culpepper ◽  
P. Roberts ◽  
R. Nichols ◽  
...  

2014 ◽  
Vol 11 (18) ◽  
pp. 5199-5213 ◽  
Author(s):  
B. Maestrini ◽  
S. Abiven ◽  
N. Singh ◽  
J. Bird ◽  
M. S. Torn ◽  
...  

Abstract. Pyrogenic organic matter (PyOM) plays an important role as a stable carbon (C) sink in the soils of terrestrial ecosystems. However, uncertainties remain about in situ turnover rates of fire-derived PyOM in soil, the main processes leading to PyOM-C and nitrogen (N) losses from the soil, and the role of N availability on PyOM cycling in soils. We measured PyOM and native soil organic carbon losses from the soil as carbon dioxide and dissolved organic carbon (DOC) using additions of highly 13C-labelled PyOM (2.03 atom %) and its precursor pinewood during 1 year in a temperate forest soil. The field experiment was carried out under ambient and increased mineral N deposition (+60 kg N-NH4NO3 ha−1 year−1). The results showed that after 1 year: (1) 0.5% of PyOM-C and 22% of wood-C were mineralized as CO2, leading to an estimated turnover time of 191 and 4 years, respectively; (2) the quantity of PyOM and wood lost as dissolved organic carbon was negligible (0.0004 ± 0.0003% and 0.022 ± 0.007% of applied-C, respectively); and (3) N additions decreased cumulative PyOM mineralization by 43%, but did not affect cumulative wood mineralization and did not affect the loss of DOC from PyOM or wood. We conclude that mineralization to CO2 was the main process leading to PyOM losses during the first year of mineralization in a forest soil, and that N addition can decrease PyOM-C cycling, while added N showed no effect on wood C cycling.


2021 ◽  
Author(s):  
Steven E Naranjo ◽  
James R Hagler ◽  
John A Byers

Abstract Conservation biological control is a fundamental tactic in integrated pest management (IPM). Greater biological control services can be achieved by enhancing agroecosystems to be more favorable to the presence, survival, and growth of natural enemy populations. One approach that has been tested in numerous agricultural systems is the deployment of synthetic chemicals that mimic those produced by the plant when under attack by pests. These signals may attract arthropod natural enemies to crop habitats and thus potentially improve biological control activity locally. A 2-yr field study was conducted in the cotton agroecosystem to evaluate the potential of synthetic methyl salicylate (MeSA) to attract native arthropod natural enemies and to enhance biological control services on two key pests. Slow-release packets of MeSA were deployed in replicated cotton plots season long. The abundance of multiple taxa of natural enemies and two major pests were monitored weekly by several sampling methods. The deployment of MeSA failed to increase natural enemy abundance and pest densities did not decline. Predator to prey ratios, used as a proxy to estimate biological control function, also largely failed to increase with MeSA deployment. One exception was a season-long increase in the ratio of Orius tristicolor (White) (Hemiptera: Anthocoridae) to Bemisia argentifolii Bellows and Perring (= Bemisia tabaci MEAM1) (Hemiptera: Aleyrodidae) adults within the context of biological control informed action thresholds. Overall results suggest that MeSA would not likely enhance conservation biological control by the natural enemy community typical of U.S. western cotton production systems.


1989 ◽  
Vol 69 (3) ◽  
pp. 551-565
Author(s):  
F. SELLES ◽  
A. J. LEYSHON ◽  
C. A. CAMPBELL

Prairie farmers are interested in applying nitrogen (N) in the fall or winter to reduce fertilizer costs and allow a better distribution of labor and machinery use. Two studies were conducted in southwestern Saskatchewan to determine the consequences of applying N in late fall. In the laboratory, fertilizer N barely penetrated into the snow at constant subzero temperatures, but under freeze-thaw conditions, urea and ammonium nitrate descended 27 cm in 3 d. In the field, ammonium nitrate and urea were applied to snow-covered and bare microplots of grass sod and cereal stubble (1981–1982) and grass sod only (1985–1986). Nitrogen from ammonium nitrate penetrated deeper into the snow than N from urea. Nitrogen recovery in April 1982 was 55–59% from ammonium nitrate and 39–51% from urea, but was near 100% for both sources on bare soil treatments in April 1986. More N was recovered when fertilizer was applied to bare than to snow-covered soil, especially during 1985–1986 when all the applied fertilizer was blown off the snow-covered plots. Mineral N generally declined from fall to spring in all treatments, probably because of denitrification and immobilization. In 1985–1986, a period of extremely low temperatures in late fall resulted in no movement or transformation of N until after early December. By late January, periods of above-zero soil temperatures resulted in substantial mineralization of soil organic N, in the fertilized plots. This apparent priming effect was attributed to perturbations in the organic matter and microbial biomass due to fertilizer application and freezing and thawing. Following this period there was a general decrease in mineral N towards spring, as observed in 1981–1982. Producers must consider the benefits of using labor and equipment more efficiently and of lower fertilizer cost in the fall against the risk of large potential N losses over winter. Key words: Urea, ammonium nitrate, N recovery, frozen soils, fertilizing in winter


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