Predicting Net Nitrogen Mineralization Over a Growing Season: Model Verification

. 2001. Pasture type and fertilization effects on soil chemical properties and nutrient redistribution. Can. J. Soil Sci. 81: 395-404. Soil samples were collected from beef pastures varying in species composition and fertilizer inputs after being grazed by cow-calf pairs for 4 yr (1995)(1996)(1997)(1998) near Brandon, Manitoba. The objective of this experiment is to examine the impact of 4 yr of continuous rotational grazing on soil chemical properties and nutrient redistribution in mixed alfalfa-grass and pure-grass pastures with or without fertilization. Pastures were established on an Orthic Black Chernozemic, fine sandy-loam soil. Compared with N-fertilized pure-grass pastures, alfalfa-grass pastures had greater seasonal soil mineral-N supply, and tended to have higher total soil C, N and organic C. In grazed systems in this environment, the use of alfalfa as the primary N source may be more profitable and sustainable than using fertilizer N. However, considering the seasonal changes in soil nitrification rate observed in alfalfa-grass pastures, caution needs to be taken when stands with high legume content are used to maximize animal performance, because this may increase the risk of N losses into the environment. Fertilization over a 5-yr period (1994)(1995)(1996)(1997)(1998) tended to lower surface soil pH. Application of P significantly increased soil "extractable" P levels in the top 15-cm soil layer. However, K fertilization only increased surface soil "extractable" K slightly compared with unfertilized pastures. There was also no effect of S application on soil "extractable" S. Zone effects on soil mineral N and soil "extractable" P, K and S were limited to the surface (0-7.5 cm). For mineral N, the zone effect seemed to be more pronounced in first rotation than in second rotation. The magnitude of K redistribution was greater than for S and P due to higher K intake and excretion. Use of rotational stocking with short grazing periods appears to have resulted in a relatively even redistribution of nutrients derived from animal excreta.

Section: Soil and Plant N Dynamicsmentioning

confidence: 99%

Pasture type and fertilization effects on soil chemical properties and nutrient redistribution

Chen¹,

McCaughey²,

Grant³

et al. 2001

“…Akinremi et al (1993) attempted to model net N min in the F-W(N'P) and Cont W (N'P) systems in the rotation study at Swift Current for a dry year (1973) and a wet year (1982) using two process-based models: CERES (Ritchie and Otter 1985) and LEACHMN (Hutson and Wagenet 1991). Because the results obtained initially were unrealistically low, the N min submodels were modified in these two models (Akinremi et al 1993;Campbell et al 1995) by adopting the potentially mineralizeable N concept of Stanford et al (1973) as modified by Campbell et al (1984Campbell et al ( , 1988 To estimate net Nmin we used spring as starting value except for Cont W (N'P) where we used Emergence so as to include fertilizer. Net Nmin for fallow was estimated as the sum of ''reasonable'' increases in NO 3 -N between sampling periods.…”

Section: Period Precip Period Air Temp ------------------------------mentioning

confidence: 99%

“…Net N mineralization increases with available water (Myers et al 1982) and is therefore greater under summer fallow than under cropped land (Campbell and Paul 1978). Nitrogen mineralization increases exponentially with temperature (Stanford et al 1973;Campbell et al 1981Campbell et al , 1988) with a Q 10 near 2.0. Nitrogen mineralization is generally greater in soils with higher organic matter content (Campbell and Souster 1982), and is near zero in frozen soils (Campbell 1978).…”

mentioning

confidence: 99%

Nitrogen mineralization under summer fallow and continuous wheat in the semiarid Canadian prairie

Campbell¹,

Zentner²,

Basnyat³

et al. 2008

M. 2008. Nitrogen mineralization under summer fallow and continuous wheat in the semiarid Canadian prairie. Can. J. Soil Sci. 88: 681Á696. The ability of soils to provide a portion of the N required by crops via N mineralization of organic matter is of economic and environmental importance. Over a 40-yr period (1967Á2006), soil NO 3 -N and plant-N measurements were made under summer fallow and in systems cropped to spring wheat (Triticum aestivum L.), on a medium-textured Orthic Brown Chernozem (Aridic Haploboroll), at Swift Current, Saskatchewan. These values were used to estimate net N mineralization (N min ). Each year, above-ground plant N was measured at harvest and soil NO 3 -N was measured before seeding, soon after harvest, and just prior to freeze-up in October. Also, in the first 18 yr of this study NO 3 -N and aboveground plant N were measured eight times between spring and fall in selected treatments; these data were used to make a more detailed estimate of N min. In a third experiment, conducted on the same soil at a nearby site in 1975, many small lysimeters were sampled six times between spring and harvest of spring wheat. We used this lysimeter study to assess the effect of N fertilizer rate and soil water on net N min. Results from the more frequent sampling were more plausible than those from sampling at three different times per year. On average, net N min in the 20-mo summer fallow period was about 118 kg ha(1 (15 kg ha (1 between harvest and the first spring, 93 kg ha (1 between the first spring and second fall, and 10 kg ha(1 between the second fall and seeding). The average net N min under a wheat crop between spring and fall was between 53 and 63 kg ha (1 . Net N min increased with water, but excessive water appeared to reduce apparent net N min , probably due to leaching and denitrification losses of N, which were not assessed in our estimation of N min . Regression analysis was used to show a positive association between net N min and precipitation, between spring and fall, for most of the systems examined. There was evidence that tillage promotes N mineralization. At normal rates of N fertilizer (i.e., B 100 kg ha(1 ), fertilizer had no effect on N min . Net N min was directly proportional to fallow frequency, averaging 68, 83, and 90 kg ha(1 yr (1 for continuous wheat, fallow-wheat-wheat, and fallow-wheat rotations, respectively. Although our results may only be applicable to medium-textured soils of similar organic matter content in the Brown and Dark Brown Chernozemic soil zone, they provide data and information against which process-based models can be tested. They also provide useful first approximations of N min measured under field conditions where few long-term data currently exist.Key words: N mineralization, plant-N, fertilizer-N, crop rotation, irrigation, tillage Campbell, C. A., Zentner, R. P., Basnyat, P., DeJong, R., Lemke, R., Desjardins, R. et Reiter, M. 2008.Mine´ralisation de l'azote sur jache`re estivale et monoculture du ble´dans les prairies semi-arides du Canada...

“…An estimate of apparent in-season mineralization (a mineralization/loss balance) using spring and fall soil residual nitrate levels and crop nitrogen uptake as employed by Campbell et al (1988) was utilized to compare differences among LEC and soil series in 1998. This simple nitrogen balance indicated that within all N rates, mineralization was in fact less, or potential losses were greater, moving from the upper to the lower LEC.…”

Section: Residual Nitratementioning

confidence: 99%

Soil moisture and nutrient variation within an undulating Manitoba landscape

Manning¹,

Fuller²,

Eilers³

et al. 2001

Soil moisture and nutrient variation within an undulating Manitoba landscape. Can. J. Soil Sci. 81: [449][450][451][452][453][454][455][456][457][458]. The use of discrete management units for variable-rate N fertilization requires that factors influencing grain yield response to N fertilizer are adequately characterized by delineating landscapes into such management units. The objective of this study was to compare the use of topographically derived landform element complexes (LEC) and the use of individual soil series as management units. Soil volumetric moisture content, nitrate-N, exchangeable ammonium-N, extractable phosphorus, exchangeable potassium, and sulphate-sulphur were studied in 10 intensively sampled transects in an undulating glacial till landscape near Miniota, Manitoba. The study site was delineated into upper, mid and lower LEC using a digital elevation model derived from relative elevation data. The LEC were useful in capturing gross variability at a manageable landscape scale. Among LEC there was a general trend of lower > mid > upper for median values of soil moisture, nitrate, phosphate, potassium and sulphate, as these attributes generally increased with convergent landscape character. Differences among LEC were often statistically significant, and relative distributions exhibited temporal persistence. The site was also stratified by soil series, including Newdale, Varcoe and Angusville soils (Black Chernozems), which were identified by examination of individual soil cores at each sample point. Stratifying the site into management units using soil genetic information, which is reflective of historical moisture conditions and biomass production, was expected to be superior. There was little advantage, however, in using soil series rather than LEC. Spatial distributions of the most agronomically relevant attributes (soil moisture and nitrate) were expressed at a landscape scale broader than that at which soil series occurred within the site. While there were important differences among soil series with respect to nutrients such as phosphate and sulphate, the site was better stratified by LEC with respect to soil moisture and nitrate. Pour fertiliser le sol avec une quantité variable d'engrais azoté, il est essentiel de bien caractériser les facteurs qui affectent la réaction du rendement grainier à l'engrais en divisant le terrain en unités agronomiques. L'étude devait comparer l'utilité de complexes d'éléments topographiques (CET) et de séries de sols comme unités agronomiques. Les auteurs ont déterminé la quantité d'eau, de N sous forme de nitrates ou d'ammonium échangeable, de phosphore extractible, de potassium échangeable et de soufre-sulfate dans un grand nombre d'échantillons prélevés le long de dix transects, sur un terrain de till glaciaire, près de Miniota, au Manitoba. Le site a été subdivisé en CET de haute, de moyenne et de faible altitude grâce à un système de modélisation numérique des hauteurs, à partir de la hauteur relative. Les CET permettent de saisir les variations gros...