Seasonal trends in the content of mineral nitrogen in solodized solonetz soil

1973 ◽  
Vol 13 (63) ◽  
pp. 423 ◽  
Author(s):  
JW McGarity ◽  
RJK Myers

Fluctuations of mineral nitrogen were studied for three years in two solodized solonetz soils at Narrabri, New South Wales, under a wheat summer-fallow management system. Changes in mineral nitrogen were related to plant uptake, soil environment characteristics (water, temperature and oxygen), and climate. NO3-N was the major form of soil mineral nitrogen, generally exceeding NH4-N with NO2-N occurring only occasionally (<1 �g N g-1). NO3-N accumulated during fallow to 67-111 kg N ha-1 in the profile just after sowing. Crop growth depleted NO3-N to 0-11 kg N ha-1 at flowering. Several significant falls in soil NO3-N (11-27 kg N ha-1) could not be accounted for by plant uptake, and were apparently caused by denitrification. Decreases due to leaching (including lateral leaching) were not detected. Redistribution of NO3-N down the profile was observed, the efficiency of leaching increasing with increased intensity of rainfall. NH4-N generally amounted to less than 25 kg N ha-1. Fluctuations in NH4-N which occurred within the profile, could not be related to observed factors and are unexplained. The effect of a drought year, 1965, was to inhibit mineral nitrogen accumulation, lessen the depth of leaching of NO3-N and depress plant uptake of nitrogen.


1988 ◽  
Vol 28 (2) ◽  
pp. 215
Author(s):  
AC Taylor ◽  
WJ Lill ◽  
AA McNeill

Dry matter and nitrogen uptake of wheat tops at flowering, dry matter and nitrogen of wheat grain at maturity, and soil mineral nitrogen (0-90 cm) at sowing and flowering, were measured at 68 sites (1 experiment per site in 5 Shires) in southern New South Wales to test the hypotheses that: (i) mineral nitrogen below 30 cm would improve the prediction of wheat yields, (ii) soil mineral nitrogen would be better indicated by wheat yields at flowering than those at maturity, and (iii) soil mineral nitrogen would be better indicated by nitrogen uptake by wheat than by dry matter yields. Mineral nitrogen concentrations in soil at depths greater than 30 cm did not improve the prediction of wheat attributes, but hypotheses (ii) and (iii) were validated. Curvilinear regressions, significant (P< 0.05) on 2 occasions, were not important in this study. The best regression of wheat dry matter at flowering against soil mineral nitrogen at sowing was a single straight line, but the best models for the other 3 wheat variables were all bilinear. The best of the latter related the uptake of nitrogen by wheat at flowering to mineral nitrogen in the soil at sowing as follows: FNUH = (31.6 � 5.9) + (0.892 � 0.110) TMNS30 and FNUL = (9.7 � 7.3) + (0.892 � 0.110) TMNS30 where FNUH is nitrogen uptake by wheat at flowering (kg/ha) in 1960, 1964 and 1966 (when Shire wheat yields were above the Shire's long term average), FNUL is nitrogen uptake by wheat at flowering (kg/ha) in 1961, 1965 and 1974 (when Shire wheat yields were below the Shire's long term average), and TMNS30 is total mineral nitrogen (0-30 cm) (kg/ha) at sowing.



1974 ◽  
Vol 14 (71) ◽  
pp. 815 ◽  
Author(s):  
FJ Hingston

Field estimates of seasonal changes in mineral nitrogen contents of nitrogen fertilized sandy soils were made at Toodyay, Meckering, Tammin, Merredin and Bodallin in the Western Australian wheatbelt during 1970. A model was used to compute water balances at each site and estimates were made of mineral nitrogen ( NH4+ and NO3-) in the soils and nitrogen in the crop. Leaching, as indicated by the distribution of ammonium and nitrate with depth in the soils, was considered in relation to the net infiltration of rainfall and drainage from the 90 cm depth of soil. Leaching of nitrate was responsible for loss of mineral nitrogen from sowing to the first sampling at Toodyay. It was unlikely that nitrate was leached below 90 cm at Meckering or Tammin, and drainage at Merredin and Bodallin was negligible. There was no drainage or net infiltration of rainfall at any site after the first sampling, between June 30 and August 11. The decreases in mineral nitrogen in the soils was about equal to the plant uptake of nitrogen in all situations where there was no leaching, except at Merredin. At that site, during the period between sowing and the second sampling (August 27), there were unexplained decreases in soil mineral nitrogen. The results show that water balance studies can give reasonable understanding of the leaching and redistribution of nitrate and ammonium in sandy soils, and hence may be used to predict for different seasonal conditions.



1986 ◽  
Vol 26 (3) ◽  
pp. 347 ◽  
Author(s):  
WM Strong ◽  
J Harbison ◽  
RGH Nielsen ◽  
BD Hall ◽  
EK Best

Available soil mineral nitrogen (N) was determined in a Darling Downs clay at intervals of 4-6 weeks throughout summer and autumn after harvest of two cereals (wheat and oats), two oilseeds (rapeseed and linseed), and four grain legumes (chickpea, fieldpea, lupin and lathyrus). Soil mineral N (0-1.2 m) at 40,68, 107, 150 and 185 days after harvest was affected (P < 0.05) by the prior crop. At 40 days it was generally higher following grain legumes (34-76 kg/ha N) than following oilseeds or cereals (16-30 kg/ha N). Net increase during the next 145 days was in the order of cereals (2 1-27 kg/ha N) < oilseeds (40 kg/ha N) <grain legumes (53-85 kg/ha N). These differences are partly accounted for by differences in the quantities of N removed in the grain of these crops. However, a large quantity of mineral N accumulated following lupin even though a large quantity (80 kg/ha) was removed in the grain.



1984 ◽  
Vol 24 (125) ◽  
pp. 244 ◽  
Author(s):  
JA Doughton ◽  
J Mackenzie

A field trial was carried out on a black earth (Waco series) at Cambooya on the Eastern Darling Downs to compare the effect of black gram, green gram, grain sorghum and a summer fallow on soil mineral nitrogen (NO3-N + NH4-N) and the yield of grain sorghum grown in the following summer. The initial sorghum treatment severely depleted soil mineral nitrogen to 120 cm; even after a 173-d fallow, there was still 34 kg/ha less nitrogen present than initially in this treatment. Black and green gram also reduced levels of soil mineral nitrogen during crop growth, but these recovered to exceed pre-trial levels by 29 and 42 kg N/ha, respectively, after a winter fallow. The fallow treatment accumulated 100 kg N/ha of mineral nitrogen between January and October, but mineralization was markedly reduced from August to October. Sorghum grown on all plots in the second summer responded markedly to prior treatments, and grain yields and responses to nitrogen applied at 0, 34 and 68 kg N/ha reflected mineral nitrogen levels at planting. Yields of sorghum grain obtained without fertilizer after black gram, green gram and fallow were 8333, 7477 and 9663 kg/ha, respectively, compared with 4658 kg/ha after sorghum. Prior crops of both grams increased sorghum yield as much as a fertilizer application of 68 kg N/ha.



2011 ◽  
Vol 342 (1-2) ◽  
pp. 221-231 ◽  
Author(s):  
Chun-Jie Li ◽  
Yu-Ying Li ◽  
Chang-Bing Yu ◽  
Jian-Hao Sun ◽  
Peter Christie ◽  
...  


Geoderma ◽  
2018 ◽  
Vol 326 ◽  
pp. 9-21 ◽  
Author(s):  
Masuda Akter ◽  
Heleen Deroo ◽  
Eddy De Grave ◽  
Toon Van Alboom ◽  
Mohammed Abdul Kader ◽  
...  


1999 ◽  
Vol 50 (2) ◽  
pp. 115-125 ◽  
Author(s):  
Maria Stenberg ◽  
Helena Aronsson ◽  
Börje Lindén ◽  
Tomas Rydberg ◽  
Arne Gustafson


2009 ◽  
Vol 21 ◽  
pp. 13-24 ◽  
Author(s):  
Y. Conrad ◽  
N. Fohrer

Abstract. This study provides results for the optimization strategy of highly parameterized models, especially with a high number of unknown input parameters and joint problems in terms of sufficient parameter space. Consequently, the uncertainty in model parameterization and measurements must be considered when highly variable nitrogen losses, e.g. N leaching, are to be predicted. The Bayesian calibration methodology was used to investigate the parameter uncertainty of the process-based CoupModel. Bayesian methods link prior probability distributions of input parameters to likelihood estimates of the simulation results by comparison with measured values. The uncertainty in the updated posterior parameters can be used to conduct an uncertainty analysis of the model output. A number of 24 model variables were optimized during 20 000 simulations to find the "optimum" value for each parameter. The likelihood was computed by comparing simulation results with observed values of 23 output variables including soil water contents, soil temperatures, groundwater level, soil mineral nitrogen, nitrate concentrations below the root zone, denitrification and harvested carbon from grassland plots in Northern Germany for the period 1997–2002. The posterior parameter space was sampled with the Markov Chain Monte Carlo approach to obtain plot-specific posterior parameter distributions for each system. Posterior distributions of the parameters narrowed down in the accepted runs, thus uncertainty decreased. Results from the single-plot optimization showed a plausible reproduction of soil temperatures, soil water contents and water tensions in different soil depths for both systems. The model performed better for these abiotic system properties compared to the results for harvested carbon and soil mineral nitrogen dynamics. The high variability in modeled nitrogen leaching showed that the soil nitrogen conditions are highly uncertain associated with low modeling efficiencies. Simulated nitrate leaching was compared to more general, site-specific estimations, indicating a higher leaching during the seepage periods for both simulated grassland systems.



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