Validation of NBudget for estimating soil N supply in Australia's northern grains region in the absence of soil test data

Soil Research ◽  
2017 ◽  
Vol 55 (6) ◽  
pp. 590 ◽  
Author(s):  
David F. Herridge
Keyword(s):  
Soil Water ◽  
Organic N ◽  
Soil N ◽  
Limited Information ◽  
Available N ◽  
Support Tool ◽  
Grain Yields ◽  
N Supply ◽  
Nitrate N ◽  
Winter Crop

Effective management of fertiliser nitrogen (N) inputs by farmers will generally have beneficial productivity, economic and environmental consequences. The reality is that farmers may be unsure of plant-available N levels in cropping soils at sowing and make decisions about how much fertiliser N to apply with limited information about existing soil N supply. NBudget is a Microsoft (Armonk, NY, USA) Excel-based decision support tool developed primarily to assist farmers and/or advisors in Australia’s northern grains region manage N. NBudget estimates plant-available (nitrate) N at sowing; it also estimates sowing soil water, grain yields, fertiliser N requirements for cereals and oilseed crops and N2 fixation by legumes. NBudget does not rely on soil testing for nitrate-N, organic carbon or soil water content. Rather, the tool relies on precrop (fallow) rainfall data plus basic descriptions of soil texture and fertility, tillage practice and information about paddock use in the previous 2 years. Use is made of rule-of-thumb values and stand-alone or linked algorithms describing, among other things, rates of mineralisation of background soil organic N and fresh residue N. Winter and summer versions of NBudget cover the 10 major crops of the region: bread wheat, durum, barley, canola, chickpea and faba bean in the winter crop version; sorghum, sunflower, soybean and mung bean in the summer crop version. Validating the winter crop version of NBudget estimates of sowing soil nitrate-N against three independent datasets (n=65) indicated generally close agreement between measured and predicted values (y=0.91x+16.8; r2=0.78). A limitation of the tool is that it does not account for losses of N from waterlogged or flooded soils. Although NBudget also predicts grain yields and fertiliser N requirements for the coming season, potential users may simply factor predicted soil N supply into their fertiliser decisions, rather than rely on the output of the tool. Decisions about fertiliser N inputs are often complex and are based on several criteria, including attitudes to risk, history of fertiliser use and costs. The usefulness and likely longevity of NBudget would be enhanced by transforming the current Excel-based tool, currently available on request from the author, to a stand-alone app or web-based tool.

Relationship of the Illinois soil nitrogen test to spring wheat yield and response to fertilizer nitrogen

2008 ◽  
Vol 88 (5) ◽  
pp. 837-848 ◽  
Author(s):  
S J Steckler ◽  
D J Pennock ◽  
F L Walley
Keyword(s):  
Soil Nitrogen ◽  
Crop Yields ◽  
Wheat Yield ◽  
N Fertilizer ◽  
Yield Response ◽  
Regression Equations ◽  
Soil N ◽  
Fertilizer N ◽  
Available N ◽  
Nitrate N

The Illinois soil N test (ISNT) has been used to distinguish between soils that are responsive and non-responsive to fertilizer N in Illinois. We examined the suitability of this test, together with more traditional measures of soil fertility, including spring nitrate-N and soil organic carbon (SOC), for predicting yield and N fertilizer response of wheat (Triticum aestivum) on hummocky landscapes in Saskatchewan. The relationship between ISNT-N and wheat yield and fertilizer N response was assessed using data and soils previously collected for a variable-rate fertilizer study. Soils were re-analyzed for ISNT-N. Our goal was to determine if ISNT-N could be used to improve the prediction of crop yields. Although ISNT-N was correlated with both unfertilized wheat yield (r = 0.467, P = 0.01) and fertilizer N response (r = -0.671, P = 0.01) when data from all study sites were combined, correlations varied according to landscape position and site. Stronger correlations between nitrate-N and both unfertilized wheat yield (r = 0.721, P = 0.01) and fertilizer N response (r = -0.690, P = 0.01) indicated that ISNT-N offered no advantage over nitrate-N. Although both tests broadly discriminated between sites with high or low N fertility, few relationships were detected on a point-by-point basis within a field. Stepwise regression equations predicting yield and yield response did not include ISNT-N, due in part to the high degree of collinearity between ISNT-N and other variables such as SOC, suggesting that ISNT-N alone was not a key indicator of soil N supply. Key words: Illinois soil nitrogen test, potentially available N, soil N, fertilizer N recommendations

Overwinter soil nitrogen dynamics in seasonally frozen soils

2000 ◽  
Vol 80 (4) ◽  
pp. 541-550 ◽  
Author(s):  
M. C. Ryan ◽  
R. G. Kachanoski ◽  
R. W. Gillham
Keyword(s):  
Soil Water ◽  
Microbial Biomass Carbon ◽  
Nitrogen Dynamics ◽  
Frozen Soil ◽  
Organic N ◽  
Soluble Nitrogen ◽  
Soil N ◽  
Freezing And Thawing ◽  
N Accumulation ◽  
Soil Microbial

An overwinter soil-monitoring study was conducted at two sites in southern Ontario. Soluble soil N accumulation at both sites occured in early winter, peaked when soil water was frozen, and then declined during the period that frozen soil water was present. The amount of soluble soil N accumulated was 48 ± 12 kg N ha−1 at one site, and 21 ± 6 kg N ha−1 at the other. In both cases, the overwinter accumulation approximately doubled the amount of soluble N in the soil. Similar trends were observed in both mineral and organic N, with 60 to 74% of the accumulation occurring in the organic form. No clear correlations between soluble nitrogen dynamics and soil extractable organic carbon or soil microbial biomass carbon dynamics were observed. Denitrification apparently occurred in shallow soil during the thaw period at one site. Since soil nitrate levels decreased before significant thawing occurred, leaching was probably not the primary dissipation mechanism. We hypothesize that the soluble N accumulation was due to death and lysis of soil microorganims during freezing and thawing. The presence of soil ice apparently decreased the lethality of the soil enviroment, allowing N dissipation to occur. Soil N dissipation could be due to gaseous losses, and is likely related to significant N2O fluxes commonly observed during spring thaw. Key words: Nitrogen, overwinter, soil ice

Soil resources and the growth and nutrition of tree seedlings near harvest gap – forest edges in interior cedar–hemlock forests of British Columbia

2006 ◽  
Vol 36 (1) ◽  
pp. 62-76 ◽  
Author(s):  
Michael B Walters ◽  
Cleo C Lajzerowicz ◽  
K David Coates
Keyword(s):  
Soil Water ◽  
Seedling Growth ◽  
N Mineralization ◽  
Forest Edge ◽  
Organic N ◽  
Tree Seedlings ◽  
Net N Mineralization ◽  
Soil N ◽  
Forest Edges ◽  
Mineral N

Observations of tree seedlings with chlorotic foliage and stunted growth near harvest gap – forest edges in interior cedar–hemlock forests inspired a study addressing the following questions: (1) Do seedling foliar chemistry, foliar nitrogen (N) versus growth relationships, and fertilizer responses suggest N-limited seedling growth? (2) Are patterns in soil characteristics consistent with N limitation, and can interrelationships among these characteristics infer causality? Our results suggest that seedling growth near gap–forest edges was colimited by N and light availability. Soil mineral N and dissolved organic N (DON) concentrations, in situ net N mineralization, and water generally increased from forest to gap, whereas N mineralization from a laboratory incubation and total N and carbon did not vary with gap–forest position. Interrelations among variables and path analysis suggest that soil water and total soil N positively affect DON concentration and N mineralization, and proximity to mature gap–forest edge trees negatively impacts mineral N concentration and water. Collectively, our results suggest that soil N levels which limit seedling growth near gap edges can be partially explained by the direct negative impacts of gap–forest edge trees on mineral N concentrations and their indirect impacts on N cycling via soil water, and not via effects on substrate chemistry.

scholarly journals Sustaining productivity of a Vertosol at Warra, Queensland, with fertilisers, no-tillage or legumes. 8. Effect of duration of lucerne ley on soil nitrogen and water, wheat yield and protein

2004 ◽  
Vol 44 (10) ◽  
pp. 1013 ◽  
Author(s):  
R. C. Dalal ◽  
E. J. Weston ◽  
W. M. Strong ◽  
M. E. Probert ◽  
K. J. Lehane ◽  
...  
Keyword(s):  
Soil Water ◽  
Soil Nitrogen ◽  
Soil Profile ◽  
Phase 1 ◽  
Wheat Yield ◽  
Soil N ◽  
N Supply ◽  
Long Duration ◽  
Moisture Deficit ◽  
Fertiliser Application

Soil nitrogen (N) supply in the Vertosols of southern Queensland, Australia has steadily declined as a result of long-term cereal cropping without N fertiliser application or rotations with legumes. Nitrogen-fixing legumes such as lucerne may enhance soil N supply and therefore could be used in lucerne–wheat rotations. However, lucerne leys in this subtropical environment can create a soil moisture deficit, which may persist for a number of seasons. Therefore, we evaluated the effect of varying the duration of a lucerne ley (for up to 4 years) on soil N increase, N supply to wheat, soil water changes, wheat yields and wheat protein on a fertility-depleted Vertosol in a field experiment between 1989 and 1996 at Warra (26°47′S, 150°53′E), southern Queensland. The experiment consisted of a wheat–wheat rotation, and 8 treatments of lucerne leys starting in 1989 (phase 1) or 1990 (phase 2) for 1, 2, 3 or 4 years duration, followed by wheat cropping. Lucerne DM yield and N yield increased with increasing duration of lucerne leys. Soil N increased over time following 2 years of lucerne but there was no further significant increase after 3 or 4 years of lucerne ley. Soil nitrate concentrations increased significantly with all lucerne leys and moved progressively downward in the soil profile from 1992 to 1995. Soil water, especially at 0.9–1.2 m depth, remained significantly lower for the next 3 years after the termination of the 4-year lucerne ley than under continuous wheat. No significant increase in wheat yields was observed from 1992 to 1995, irrespective of the lucerne ley. However, wheat grain protein concentrations were significantly higher under lucerne–wheat than under wheat–wheat rotations for 3–5 years. The lucerne yield and soil water and nitrate-N concentrations were satisfactorily simulated with the APSIM model. Although significant N accretion occurred in the soil following lucerne leys, in drier seasons, recharge of the drier soil profile following long duration lucerne occurred after 3 years. Consequently, 3- and 4-year lucerne–wheat rotations resulted in more variable wheat yields than wheat–wheat rotations in this region. The remaining challenge in using lucerne–wheat rotations is balancing the N accretion benefits with plant-available water deficits, which are most likely to occur in the highly variable rainfall conditions of this region.

scholarly journals Subcritical water extraction to isolate kinetically different soil nitrogen fractions

2013 ◽  
Vol 10 (11) ◽  
pp. 7435-7447 ◽  
Author(s):  
S. Sleutel ◽  
M. A. Kader ◽  
K. Demeestere ◽  
C. Walgraeve ◽  
J. Dewulf ◽  
...  
Keyword(s):  
Bonding Strength ◽  
N Mineralization ◽  
Subcritical Water ◽  
Water Extraction ◽  
Organic N ◽  
Soil N ◽  
Subcritical Water Extraction ◽  
Available N ◽  
Upland Soils ◽  
N Fractions

Abstract. Soil organic N is largely composed of inherently biologically labile proteinaceous N and its persistence in soil is mainly explained by stabilization through binding to minerals and other soil organic matter (SOM) components at varying strengths. In order to separate kinetically different soil N fractions we hypothesize that an approach which isolates soil N fractions on the basis of bonding strength is required, rather than employing chemical agents or physical methods. We developed a sequential subcritical water extraction (SCWE) procedure at 100, 150 and 200 °C to isolate SOM fractions. We assessed these SCWE N fractions as predictors for aerobic and anaerobic N mineralization measured from 25 paddy soil cores in incubations. SCWE organic carbon (SCWE OC) and N (SCWE N) increased exponentially with the increase of temperature and N was extracted preferentially over OC. The efficiency of SCWE and the selectivity towards N were both lower in soils with increasingly reactive clay mineralogy. Stepwise linear regression found no relations between the SCWE fractions and the anaerobic N mineralization rate but instead with pH and a model parameter describing the temperature dependency of SCWE extraction. Both were linked to texture, mineralogy and content of pedogenic oxides, which suggests an indirect relation between anaerobic NH4+ release and these edaphic soil factors. N mineralization appeared to be largely decoupled from SOM quantity and quality. From the present study on young paddy soils low in pedogenic oxides and with high fixed NH4+ content we cannot infer the performance of SCWE to isolate bio-available N in more developed upland soils. There may be potential to separate kinetically different SOM pools from upland soils because 1° for aerobic N mineralization at 100–150 °C SCWE N was the best predictor; and 2° SCWE selectively extracted N over C and this preference depended on the mineralogical composition. Hence N fractions differing in bonding strength with minerals or SOM might be isolated at different temperatures, and specifically this association has frequently been found a prominent stabilization mechanism of N in temperate region cropland soils.

Nitrogen fixation and soil nitrate interactions in field-grown chickpea (Cicer arietinum) and fababean (Vicia faba)

2002 ◽  
Vol 53 (5) ◽  
pp. 599 ◽  
Author(s):  
J. E. Turpin ◽  
D. F. Herridge ◽  
M. J. Robertson
Keyword(s):  
Vicia Faba ◽  
Cicer Arietinum ◽  
N2 Fixation ◽  
Soil Nitrate ◽  
Soil N ◽  
Total N ◽  
Grain Yields ◽  
N Supply ◽  
Total Plant ◽  
N Rates

Soil in which nodulated legumes are growing often contains more nitrate nitrogen (N) than soil in which unnodulated legumes or non-legumes are growing. There is conjecture, however, as to whether the extra or ‘spared’ N is due to reduced use of soil N by the legume or to net mineralisation of legume root and nodular N. We report results of a field experiment to quantify and compare, at different levels of soil-N supply, N2 fixation, and soil-N use by chickpea (Cicer arietinum) and fababean (Vicia faba). Wheat (Triticum aestivum) was included as a non-N2-fixing control. Plants of the 3 species were grown on a low-nitrate Vertosol with fertiliser N rates of 0, 50, and 100 kg/ha (0N, 50N, and 100N), applied 6 weeks before sowing. Samples were collected at sowing and at 64, 100, 135, and 162 days after sowing (DAS) for analysis of soil nitrate, root, and grain dry matter (DM) and N and shoot DM, N, and 15N. The latter was used to estimate the percentage (%Ndfa) and total N fixed by the 2 legumes. Soil nitrate levels to a depth of 1.8 m at sowing were 11–17 kg N/ha (0N), 41–55 kg N/ha (50N), and 71–86 kg N/ha (100N). Grain yields of the 2 legumes were unaffected by soil-N supply (fertiliser N treatment), being 2.0–2.4 t/ha for chickpea and 3.7–4.6 t/ha for fababean. Wheat grain yields varied from 1.6 t/ha (0N) to 4.8 t/ha (100N). Fababean fixed more N than chickpea. Values (total plant including roots) were 209–275 kg/ha for fababean and 146–214 kg/ha for chickpea. Corresponding %Ndfa values were 69–88% (fababean) and 64–85% (chickpea). Early in crop growth, when soil N supply was high in the 100N treatment, fababean maintained a higher dependence on N2 fixation than chickpea (Ndfa of 45% v. 12%), fixed greater amounts of N (57 v. 16 kg/ha), and used substantially less soil N (69 v. 118 kg/ha). In this situation, soil N sparing was observed, with soil nitrate levels significantly higher in the fababean plots (P < 0.05) than under chickpea or wheat. At the end of growth season, however, there were no crop effects on soil nitrate levels. Soil N balances, which combined crop N fixed as inputs and grain N as outputs, were positive for the legumes, with ranges 80–135 kg N/ha for chickpea and 79–157 kg N/ha for fababean, and negative for wheat (–20 to –66 kg N/ha). We concluded that under the starting soil nitrate levels in this experiment, levels typical of many cropping soils in the region, high-biomass fababean and chickpea crops will not spare significant amounts of soil N. In situations of higher soil nitrate and/or smaller biomass crops with less N demand, nitrate sparing may occur, particularly with fababean.

Ectomycorrhizal fungi and the nitrogen economy of conifers — implications for genecology and climate change mitigation

Botany ◽  
2014 ◽  
Vol 92 (6) ◽  
pp. 417-423 ◽  
Author(s):  
J.M. Kranabetter
Keyword(s):  
Climate Change ◽  
Climate Change Mitigation ◽  
N Uptake ◽  
Organic N ◽  
Soil N ◽  
N Supply ◽  
Wide Range ◽  
Forest Genetic ◽  
Spatial Attributes ◽  
Change Mitigation

The nitrogen (N) economy of conifers is hypothesized to reflect three spatially defined and interacting sources of variability in forest nutrition. These include the physiological adaptations of the host tree (N uptake capacities among populations), matched to the particular amount and nature of soil N supply (organic N, NH4+, and NO3–), as mediated by communities of site-adapted ectomycorrhizal (EM) fungi. The spatial attributes of an N economy may vary considerably over the ranges of tree species because of wide gradients in climate and soil fertility, underpinning a potentially important aspect of conifer genecology with implications for climate change mitigation. The evidence for an intersection of N supply with host demand, as mediated by EM fungi, will be briefly reviewed and then evaluated in light of assisted migration studies involving provenance trials of coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) in southwestern British Columbia. The trials were established across a wide range of site types, and so they provide valuable data on host response to gradations in soil N supply and interactions with local EM fungal communities. Preliminary results and knowledge gaps will be discussed under the framework of an N economy and management of forest genetic resources.

Urea fertilizations of a Norway spruce stand: effects on nitrogen in soil water and field-layer vegetation after final felling

2003 ◽  
Vol 33 (2) ◽  
pp. 375-384 ◽  
Author(s):  
Eva Ring ◽  
Johan Bergholm ◽  
Bengt A Olsson ◽  
Gunnar Jansson
Keyword(s):  
Soil Water ◽  
Norway Spruce ◽  
Organic N ◽  
First Year ◽  
Total N ◽  
Urea Treatment ◽  
Field Layer ◽  
Nitrate N ◽  
Ammonium N ◽  
The Difference

Effects of previous fertilization with N (in total, 600 kg urea-N·ha–1 applied in 1976, 1980, and 1985) were studied after final felling in 1992 of a Norway spruce (Picea abies (L.) Karst.) stand in southern Sweden. The logging residues were removed from the site. In the clearcut, soil water at 50 cm depth was sampled 16 times with ceramic suction samplers (P80) in experimental plots during 1992–1995. The biomass and N content of the field layer was measured on seven occasions. The N storage of the field layer was significantly (p < 0.05) higher in the urea treatment than in the control. Significant interactions between treatment and time were found in soil water for nitrate-N and total N but not for ammonium-N, organic N, and pH. During the first year after final felling, nitrate-N tended to increase faster in the urea treatment than in the control. After a period with similar concentrations in both treatments, nitrate-N in the urea treatment declined while at the same time, a peak was observed in the control showing four to seven times higher concentrations than in the urea treatment. At the end of the study, the concentrations still appeared to be highest in the control. Thus, the study demonstrated the importance of using a sufficiently long study period when investigating environmental effects. Total leaching of nitrate-N from the urea treatment was roughly 40% ([Formula: see text]20 kg·ha–1) less than that from the control. The difference in leaching may be partly explained by the greater accumulation of N in the field-layer vegetation in the urea treatment.

scholarly journals Nitrogen balance in soil under eucalyptus plantations

2012 ◽  
Vol 36 (4) ◽  
pp. 1239-1248 ◽  
Author(s):  
Patrícia Anjos Bittencourt Barreto ◽  
Antonio Carlos da Gama-Rodrigues ◽  
Emanuela Forestieri da Gama-Rodrigues ◽  
Nairam Félix de Barros
Keyword(s):  
N Balance ◽  
Organic N ◽  
Soil N ◽  
Mineral N ◽  
Wood Harvesting ◽  
N Supply ◽  
Eucalyptus Plantations ◽  
Different Ages ◽  
The Difference ◽  
N Pool

An understanding of the role of organic nitrogen (N) pools in the N supply of eucalyptus plantations is essential for the development of strategies that maximize the efficient use of N for this crop. This study aimed to evaluate the distribution of organic N pools in different compartments of the soil-plant system and their contributions to the N supply in eucalyptus plantations at different ages (1, 3, 5, and 13 years). Three models were used to estimate the contributions of organic pools: Model I considered N pools contained in the litterfall, N pools in the soil microbial biomass and available soil N (mineral N); Model II considered the N pools in the soil, potentially mineralizable N and the export of N through wood harvesting; and Model III (N balance) was defined as the difference between the initial soil N pool (0-10 cm) and the export of N, taking the application of N fertilizer into account. Model I showed that N pools could supply 27 - 70 % of the N demands of eucalyptus trees at different ages. Model II suggested that the soil N pool may be sufficient for 4 - 5 rotations of 5 years. According to the N balance, these N pools would be sufficient to meet the N demands of eucalyptus for more than 15 rotations of 5 years. The organic pools contribute with different levels of N and together are sufficient to meet the N demands of eucalyptus for several rotations.

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