Evaluation of LEACHMN for simulating seasonal changes in plant available nitrogen across a variable landscape

2007 ◽  
Vol 87 (4) ◽  
pp. 369-381 ◽  
Author(s):  
H. Dadfar ◽  
B D Kay ◽  
R. Pararajasingham ◽  
R S Dharmakeerthi ◽  
E G Beauchamp
Keyword(s):  
Seasonal Changes ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
Available N ◽  
Additional Tool ◽  
Potential Value ◽  
Growing Seasons ◽  
Using Data ◽  
N Management

A model that accurately simulates the seasonal variation in nitrogen (N) dynamics may represent an important additional tool in N management. The objectives of this study were to evaluate whether seasonal changes in the amount of N that becomes available to a maize crop in a variable landscape can be simulated with LEACHMN and, in particular, to assess the potential value of LEACHMN in estimating N available at the time of the presidedress soil nitrate test (PSNT). Soil mineral N (SMN) and shoot N were measured biweekly over seven growing seasons in corn (Zea Mays L.) grown under conventional tillage in a variable landscape in Southern Ontario, Canada. The model was calibrated using data from 2002 and 2003 from each of five positions in the landscape and then evaluated using data from the 1997–2001 growing seasons. Although the model under-estimated SMN and over-estimated shoot N, the model was more successful in simulating the sum, defined as plant available N (PAN). Simulations of PAN were best at the summit and shoulder positions. The agreement between measured and simulated PAN were poorest early in the season. Although the accuracy of PAN simulations late in the growing season indicates this model has potential value in N management decisions, the errors in simulating SMN early in the season suggest adjustments are required before it can be used, along with other tools, as a substitute for the PSNT in cool humid environments. Key words: Soil mineral N, Plant available N, variable landscapes, LEACHMN

Availability of residual fertilizer nitrogen in a Darling Downs black earth in the presence and absence of wheat straw

1987 ◽  
Vol 27 (2) ◽  
pp. 295 ◽  
Author(s):  
WM Strong ◽  
RC Dalal ◽  
JE Cooper ◽  
PG Saffigna
Keyword(s):  
Application Rate ◽  
Residual Effects ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
N Application ◽  
Available N ◽  
Preceding Crop ◽  
Supplementary Irrigation ◽  
N Pool

Mineralisation and availability of residual fertiliser nitrogen (N) was studied in pots during December-October with and without the addition of straw (0-7.5 t/ha) on a Darling Downs black earth previously cropped with wheat. Soil (0-0.2 m) and straw were collected from field plots in which wheat was grown previously with supplementary irrigation and fertiliser N applied at 0, 100, 200, 300 or 400 kg/ha. At the end of the fallow, in June, there was a net increase in soil mineral N of between 0.7 and 11.1 mg/kg where fertiliser was applied to the preceding crop. The increase represented between 2 and 9% of the original N application and was larger with increasing N application rate and smaller with increasing rate of straw addition. Straw addition caused a substantial decrease in mineral N which was still evident in June and October, 162 and 305 days respectively following straw addition. Soil mineral N decreased linearly at the rate of 5 kg N/t of straw added up to 7.5 t/ha. The net effect of prior N applications on the quantity of N available to wheat plants was equivalent to 10-23% of the quantity of N applied to the preceding crop in the absence of straw and only 4% in the presence of straw. Residual effects of prior N applications on the quantity of N available for wheat plants was generally greater than was evident as soil mineral N in June. During crop growth, additional available N may have been released from the microbial soil N pool, especially where 200 or 400 kg/ha of N had been applied. Straw addition resulted in more microbial biomass throughout the fallow. The larger microbial N pool, however, contained less N than that immobilised due to straw addition. Thus, regardless of prior N application, less N was available to wheat plants in the presence than in the absence of straw of preceding wheat crops.

Mineral nitrogen supply from pastures to cereals in three northern Victorian environments

2006 ◽  
Vol 46 (1) ◽  
pp. 59 ◽  
Author(s):  
R. H. Harris ◽  
M. J. Unkovich ◽  
J. Humphris
Keyword(s):  
Grain Yield ◽  
Crop Production ◽  
Mineral Nitrogen ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Short Term ◽  
Potential Yield ◽  
Mineral N ◽  
Available N ◽  
Cereal Grain

An experiment at 3 sites (Birchip, Elmore and Speed) in the northern Victorian cropping belt compared dry matter (DM) production of short-term (2 year) pastures and their contributions to soil mineral nitrogen (N) and subsequent wheat and barley production. The pastures included different varieties of subterranean clover, annual medic and lucerne, and these were compared with ryegrass-dominant pasture, which represented the experimental control. More productive legume pastures generally resulted in greater accumulation of soil mineral N at sowing of the following cereal at both Elmore and Speed; however, at Birchip, soil mineral N remained high under all treatments. At Elmore and Speed, significant (P<0.10) positive relationships were observed between available N at sowing and subsequent wheat and barley production. Cereal grain yield at Birchip was not associated with available N at sowing. The quantities of soil mineral N available at sowing (152 kg/ha) of the cereals were in excess of crop demand at Birchip. At Elmore, the soil mineral N supply (83 kg/ha) was below that required for wheat and barley to reach their water-limited potential yield (20 kg grain/mm of growing season rainfall). However, at Speed, the supply of soil mineral N (63 kg/ha) was sufficient to achieve the water-limited potential grain yield and to produce malting-grade barley, but not sufficient to elevate wheat grain protein concentrations above 11.5%. In environments with low soil N levels, the amount of residual N following short-term pastures increased the availability of N to following cereals. Whether this is sufficient to satisfy subsequent crop demand is largely determined by water availability in the year of cropping. In cases where available N is already high, short-term pasture phases may have little effect on increasing crop production.

scholarly journals Growth and Yield of Broccoli as Affected by the Nitrogen Content of Transplants and the Timing of Nitrogen Fertilization

HortScience ◽  
2005 ◽  
Vol 40 (5) ◽  
pp. 1320-1323 ◽  
Author(s):  
Carmen Feller ◽  
Matthias Fink
Keyword(s):  
Field Experiments ◽  
N Fertilizer ◽  
Growth And Yield ◽  
Growth Stages ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
N Content ◽  
Available N ◽  
N Supply

The nitrogen requirement of broccoli (Brassica oleracea var. italica) ranges from 300 to 465 kg·ha–1. Recommendations for N fertilization are accordingly high. High fertilizer rates applied at planting result in a high soil mineral N content that remains high for weeks because the N requirement of the crop is low at early growth stages. Therefore, the risk of leaching is high for several weeks until the available N is finally taken up by the crop. Our study had two objectives: 1) to quantify yield responses to preplant fertilization, and 2) to test our hypothesis that the preplant fertilization rate could be reduced without yield losses by increasing the N content in the transplants and improving crop establishment. Field experiments were carried out on transplants with four levels of N content in dry matter (0.018 to 0.038 g·g–1 dry weight), which were tested in all combinations with four fertilization timings. All treatments received the same amount of N fertilizer (270 and 272 kg·ha–1 in 2001 and 2002, respectively), but with different rates of supply at the time of planting (0 to 90 kg·ha–1 N fertilizer plus 30 and 28 kg·ha–1 soil mineral N in 2001 and 2002, respectively). Total and marketable yields increased significantly with an increasing N supply at time of planting. In our experiments, in which topdressing was applied 25 days after planting, an N supply at planting of 80 to 118 kg·ha–1 was required to obtain maximum marketable yields. The N content in transplants had little effect on growth and yield, and there were no significant interactions between the N content in the transplant and fertilizer timing.

scholarly journals Nitrogen enrichment enhances the dominance of grasses over forbs in a temperate steppe ecosystem

2011 ◽  
Vol 8 (8) ◽  
pp. 2341-2350 ◽  
Author(s):  
L. Song ◽  
X. Bao ◽  
X. Liu ◽  
Y. Zhang ◽  
P. Christie ◽  
...  
Keyword(s):  
Species Richness ◽  
Aboveground Biomass ◽  
N Deposition ◽  
Soil Mineral N ◽  
N Addition ◽  
Soil Mineral ◽  
Temperate Steppe ◽  
Mineral N ◽  
N Concentration ◽  
Steppe Ecosystem

Abstract. Chinese grasslands are extensive natural ecosystems that comprise 40 % of the total land area of the country and are sensitive to N deposition. A field experiment with six N rates (0, 30, 60, 120, 240, and 480 kg N ha−1 yr−1) was conducted at Duolun, Inner Mongolia, during 2005 and 2010 to identify some effects of N addition on a temperate steppe ecosystem. The dominant plant species in the plots were divided into two categories, grasses and forbs, on the basis of species life forms. Enhanced N deposition, even as little as 30 kg N ha−1 yr−1 above ambient N deposition (16 kg N ha−1 yr−1), led to a decline in species richness. The cover of grasses increased with N addition rate but their species richness showed a weak change across N treatments. Both species richness and cover of forbs declined strongly with increasing N deposition as shown by linear regression analysis (p < 0.05). Increasing N deposition elevated aboveground production of grasses but lowered aboveground biomass of forbs. Plant N concentration, plant δ15N and soil mineral N increased with N addition, showing positive relationships between plant δ15N and N concentration, soil mineral N and/or applied N rate. The cessation of N application in the 480 kg N ha−1 yr−1 treatment in 2009 and 2010 led to a slight recovery of the forb species richness relative to total cover and aboveground biomass, coinciding with reduced plant N concentration and soil mineral N. The results show N deposition-induced changes in soil N transformations and plant N assimilation that are closely related to changes in species composition and biomass accumulation in this temperate steppe ecosystem.

Gross rates of soil N2O emission and uptake and denitrification gene abundance in temperate cropland agroforestry and monoculture systems

2021 ◽  
Author(s):  
Jie Luo ◽  
Lukas Beule ◽  
Guodong Shao ◽  
Edzo Veldkamp ◽  
Marife D. Corre
Keyword(s):  
Greenhouse Gas ◽  
Management Systems ◽  
Soil N ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
Total N ◽  
Soil P ◽  
Gene Abundance ◽  
Denitrification Gene

&lt;p&gt;Monoculture croplands are considered as major sources of the greenhouse gas, nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O). The conversion of monoculture croplands to agroforestry systems, e.g., integrating trees within croplands, is an essential climate-smart management system through extra C sequestration and can potentially mitigate N&lt;sub&gt;2&lt;/sub&gt;O emissions. So far, no study has systematically compared gross rates of N&lt;sub&gt;2&lt;/sub&gt;O emission and uptake between cropland agroforestry and monoculture. In this study, we used an in-situ &lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;2&lt;/sub&gt;O pool dilution technique to simultaneously measure gross N&lt;sub&gt;2&lt;/sub&gt;O emission and uptake over two consecutive growing seasons (2018 - 2019) at three sites in Germany: two sites were on Phaeozem and Cambisol soils with each site having a pair of cropland agroforestry and monoculture systems, and an additional site with only monoculture on an Arenosol soil prone to high nitrate leaching. Our results showed that cropland agroforestry had lower gross N&lt;sub&gt;2&lt;/sub&gt;O emissions and higher gross N&lt;sub&gt;2&lt;/sub&gt;O uptake than in monoculture at the site with Phaeozem soil (P &amp;#8804; 0.018 &amp;#8211; 0.025) and did not differ in gross N&lt;sub&gt;2&lt;/sub&gt;O emissions and uptake with cropland monoculture at the site with Cambisol soil (P &amp;#8805; 0.36). Gross N&lt;sub&gt;2&lt;/sub&gt;O emissions were positively correlated with soil mineral N and heterotrophic respiration which, in turn, were correlated with soil temperature, and with water-filled pore space (WFPS) (r = 0.24 &amp;#8210; 0.54, P &lt; 0.01). Gross N&lt;sub&gt;2&lt;/sub&gt;O emissions were also negatively correlated with nosZ clade I gene abundance (involved in N&lt;sub&gt;2&lt;/sub&gt;O-to-N&lt;sub&gt;2&lt;/sub&gt; reduction, r = -0.20, P &lt; 0.05). These findings showed that across sites and management systems changes in gross N&lt;sub&gt;2&lt;/sub&gt;O emissions were driven by changes in substrate availability and aeration condition (i.e., soil mineral N, C availability, and WFPS), which also influenced denitrification gene abundance. The strong regression values between gross N&lt;sub&gt;2&lt;/sub&gt;O emissions and net N&lt;sub&gt;2&lt;/sub&gt;O emissions (R&lt;sup&gt;2 &lt;/sup&gt;&amp;#8805; 0.96, P &lt; 0.001) indicated that gross N&lt;sub&gt;2&lt;/sub&gt;O emissions largely drove net soil N&lt;sub&gt;2&lt;/sub&gt;O emissions. Across sites and management systems, annual soil gross N&lt;sub&gt;2&lt;/sub&gt;O emissions and uptake were controlled by clay contents which, in turn, correlated with indices of soil fertility (i.e., effective cation exchange capacity, total N, and C/N ratio) (Spearman rank&amp;#8217;s rho = -0.76 &amp;#8211; 0.86, P &amp;#8804; 0.05). The lower gross N&lt;sub&gt;2&lt;/sub&gt;O emissions from the agroforestry tree rows at two sites indicated the potential of agroforestry in reducing soil N&lt;sub&gt;2&lt;/sub&gt;O emissions, supporting the need for temperate cropland agroforestry to be considered in greenhouse gas mitigation policies.&lt;/p&gt;

Winter wheat yield and nitrous oxide emissions in response to cowpea-based green manure and nitrogen fertilization

2019 ◽  
Vol 56 (2) ◽  
pp. 239-254 ◽  
Author(s):  
Tanka P. Kandel ◽  
Prasanna H. Gowda ◽  
Brian K. Northup ◽  
Alexandre C. Rocateli
Keyword(s):  
Nitrous Oxide ◽  
Winter Wheat ◽  
Green Manure ◽  
Inorganic Nitrogen ◽  
Wheat Yield ◽  
Nitrous Oxide Emissions ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
Winter Wheat Yield

AbstractThe aim of this study was to compare the effects of cowpea green manure and inorganic nitrogen (N) fertilizers on yields of winter wheat and soil emissions of nitrous oxide (N2O). The comparisons included cowpea grown solely as green manure where all biomass was terminated at maturity by tillage, summer fallow treatments with 90 kg N ha−1 as urea (90-N), and no fertilization (control) at planting of winter wheat. Fluxes of N2O were measured by closed chamber methods after soil incorporation of cowpea in autumn (October–November) and harvesting of winter wheat in summer (June–August). Growth and yields of winter wheat and N concentrations in grain and straw were also measured. Cowpea produced 9.5 Mg ha−1 shoot biomass with 253 kg N ha−1 at termination. Although soil moisture was favorable for denitrification after soil incorporation of cowpea biomass, low concentrations of soil mineral N restricted emissions of N2O from cowpea treatment. However, increased concentrations of soil mineral N and large rainfall-induced emissions were recorded from the cowpea treatment during summer. Growth of winter wheat, yield, and grain N concentrations were lowest in response to cowpea treatment and highest in 90-N treatment. In conclusion, late terminated cowpea may reduce yield of winter wheat and increase emissions of N2O outside of wheat growing seasons due to poor synchronization of N mineralization from cowpea biomass with N-demand of winter wheat.

Cutting management and alfalfa stand age effects on organically grown corn grain yield and soil N availability

2017 ◽  
Vol 34 (2) ◽  
pp. 144-154 ◽  
Author(s):  
Adria L. Fernandez ◽  
Karina P. Fabrizzi ◽  
Nicole E. Tautges ◽  
John A. Lamb ◽  
Craig C. Sheaffer
Keyword(s):  
The Other ◽  
Stand Age ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
No Removal ◽  
Soil C ◽  
Biomass Removal ◽  
Potentially Mineralizable N ◽  
Corn Grain

AbstractAlfalfa is recommended as a rotational crop in corn production, due to its ability to contribute to soil nitrogen (N) and carbon (C) stocks through atmospheric N2fixation and above- and belowground biomass production. However, there is little information on how alfalfa management practices affect contributions to soil and subsequent corn crop yields, and research has not been targeted to organic systems. A study was conducted to determine the effects of alfalfa stand age, cutting frequency and biomass removal on soil C and N status and corn yields at three organically managed Minnesota locations. In one experiment, five cutting treatments were applied in nine environments: two, three and four cuts with biomass removal; three cuts with biomass remaining in place; and a no-cut control. In the other experiment, corn was planted following 1-, 2-, 3- or 4-year-old alfalfa stands and a no-alfalfa control. Yield was measured in the subsequent corn crop. In the cutting experiment, the two- and three-cut treatments with biomass removal reduced soil mineral N by 12.6 and 11.5%, respectively, compared with the control. Potentially mineralizable N (PMN) was not generally affected by cutting treatments. The three-cut no-removal increased potentially mineralizable C by 17% compared with the other treatments, but lowered soil total C in two environments, suggesting a priming effect in which addition of alfalfa biomass stimulated microbial mineralization of native soil C. Although both yields and soil mineral N tended to be higher in treatments where biomass remained in place, this advantage was small and inconsistent, indicating that farmers need not forgo hay harvest to obtain the rotational benefits of an alfalfa stand. The lack of overall correlation between corn grain yields and mineral and potentially mineralizable N suggests that alfalfa N contribution was not the driver of the yield increase in the no-removal treatments. Alfalfa stand age had inconsistent effects on fall-incorporated N and soil N and C parameters. Beyond the first year, increased alfalfa stand age did not increase soil mineral N or PMN. However, corn yield increased following older stands. Yields were 29, 77 and 90% higher following first-, second- and third-year alfalfa stands than the no-alfalfa control, respectively. This indicates that alfalfa may benefit succeeding corn through mechanisms other than N contribution, potentially including P solubilization and weed suppression. These effects have been less studied than N credits, but are of high value in organic cropping systems.

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