scholarly journals Dynamics of mineral nitrogen in topsoil, during regrowth of pasture in two contrasting grassland systems

1991 ◽  
pp. 203-208
Author(s):  
B.E. Ruz-Jerez ◽  
P.Roger Ball ◽  
R.E. White
Keyword(s):  
Mineral Nitrogen ◽  
Organic N ◽  
Soil Cores ◽  
Soil Mineral Nitrogen ◽  
Mineral N ◽  
Undisturbed Soil ◽  
Net Mineralisation ◽  
Organic Combination ◽  
Undisturbed Soil Cores ◽  
Intensive System

Changes in soil mineral nitrogen(N) were monitored during regrowth of pasture between consecutive grazings in two contrasting grassland systems; Grass-clover (the norm in NZ) and a more intensive system, Grass+N400 (pure grass + 400 kg fertiliser N/ha/year). The experiment was carried out during autumn at DSIR Grasslands.Palmerston North. Net mineralisation of N under field conditions was estimate_d- i~n- an ancillary experiment, using soil samples from undisturbed soil cores contained in PVC tubes. The dynamics of mineral N in soil were dominated by a 'pulse' of ammonium, observable soon after grazing. Nitrification proceeded rapidly thereafter. Mineral N in soil then progressively declined, much of it going into organic combination presumably through uptake by plants. Since nitrate formation in the soil is minimised by maximising the residence time of N in plant (organic) form, differentmanagementoptions(varyinginfrequency and intensity of defoliation) may have important influences, not only on pasture utilisation and production, but also on the management of mineral N in the soil-plant-animal complex. Tubes embedded in soil and incubated in the field have provided some additional, useful perspectives. There was only limitedevidence for significant net mineralisation of organic N throughout the period of regrowth. Analyses of individual soil cores demonstrated a sharp contrast between the pasture at large and the 10 - 15% of total area influenced by urine from the previous grazing, in terms of mineral N content. 'Averaging' these by bulking numerous cores into a composite sample can provide an accurate quantitative estimate of mineral N, which can be related to herbage uptake of N over the whole area. But if losses of N (by leaching or volatilisation) are disproportionate to the concentration of mineral N in affected and unaffected volumes of soil, then bulking samples and averaging will not be the most appropriate way to estimate these losses. The results of this study point to the importance of the urine of grazing ruminants as a N substrate for pasture regrowth in the absence of fertiliser N. At the same time, urine patches provide the main avenue for Nescape to the wider environment from developed pastures. Keywords mineral N, N in pastures, N cycling by animals

Nutrient leaching losses from undisturbed soil cores following applications of piggery wastewater

Soil Research ◽  
2002 ◽  
Vol 40 (3) ◽  
pp. 515 ◽  
Author(s):  
I. R. Phillips
Keyword(s):  
Organic N ◽  
Soil Core ◽  
Soil Cores ◽  
Organic P ◽  
Piggery Wastewater ◽  
Undisturbed Soil ◽  
Leaching Losses ◽  
Land Disposal ◽  
Undisturbed Soil Cores ◽  
Soil Colloids

Land disposal of wastewater from intensive livestock industries can result in large amounts of nutrients and salts being applied to soils. When irrigated at rates to meet crop phosphorus (P) requirements, nitrogen (N), calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), chloride (Cl), and sulfate (SO4) applied in the wastewater often exceed crop demands, and are susceptible to leaching. Leaching of surface-applied piggery wastewater was investigated using large undisturbed soil cores (30 cm i.d. by 60 or 75 cm long) from 2 piggery wastewater disposal areas (Site 1, Vertosol; Site 2, Sodosol) in south-east Queensland. About 3% of the total wastewater P applied to the Vertosol, and about 10% of that applied to the sodosol, was leached. The magnitude of these losses was consistent with the chemical properties of each soil, and the availability of P sorption sites (i.e. hydrous Fe oxides). The major forms of P in the leachate included both molybdate reactive P (MRP) and unreactive P (UP, includes dissolved organic P, soluble organic P, particulate P, and non-reactive P). Phosphorus leached from the Vertosol was largely (≈80%) as UP because the MRP was sorbed by the soil colloids. Much of the P leached from the sodosol was present as MRP (≈70%) because the wastewater applied to this soil also contained about 70% MRP, and this soil had only a limited ability to sorb MRP. Losses of nitrogen (N) were found to be of a major environmental concern. Both wastewater samples contained very high levels of N, with ammonium (NH4-N) making up about 80% of the total Kjeldahl N (TKN) and organic N about 20%. Negligible amounts of applied NH4-N were detected either sorbed by the soil or in the leachate because it was converted to nitrate (NO3-N) within the soil core. This NO3-N was highly mobile, and was readily leached from the soil cores. Nitrogen represented the major limitation to the long-term use of land for disposal of piggery wastewater. For land disposal to be an effective management option, N applied in piggery wastewater may need to be limited to about 200 kg/ha.year. Significant amounts of Ca, Mg, K, and Na applied in the wastewater were leached from the soil cores. It is recommended that more attention be placed on the impact of N (TKN, NH4-N, and NO3-N), Ca, Mg, K, and Na on the receiving soil and water environments rather than focussing primarily on wastewater P. Management strategies should be developed for disposal sites to minimise leaching losses by maximising nutrient removal from the soil solution through crop uptake, reaction with the soil colloids, and efficient irrigation practices. nitrogen, phosphorus, cations, nitrification, piggery wastewater.

The source of mineral nitrogen for cereals in south-eastern Australia

1998 ◽  
Vol 49 (3) ◽  
pp. 511 ◽  
Author(s):  
J. F. Angus ◽  
A. F. van Herwaarden ◽  
D. P. Heenan ◽  
R. A. Fischer ◽  
G. N. Howe
Keyword(s):  
Root Zone ◽  
Growing Season ◽  
Crop Growth ◽  
Mineral Nitrogen ◽  
Soil Mineral ◽  
Soil Mineral Nitrogen ◽  
Mineral N ◽  
Total N ◽  
Eastern Australia ◽  
Net Mineralisation

The relative importance of soil mineral nitrogen (N) available at the time of sowing ormineralised during the growing season was investigated for 6 crops of dryland wheat. The soil mineral N in the root-zone was sampled at sowing and maturity and the rate of net mineralisation in the top 10 cm was estimated by sequential sampling throughout the growing season, using an in situ method. Mineralisation during crop growth was modelled in relation to total soil N, ambient temperature, andsoil water content. Mineral N accumulated before sowing varied by a factor of 3 between the sites (from 67 to 195 kgN/ha), while the net mineralisation during crop growth varied by a factor of 2 (from 43 to 99 kgN/ha). The model indicated that 0·092% of total N was mineralised per day when temperature and water were not limiting, with rates decreasing for lower temperatures and soil water contents. When tested with independent data, the model predicted the mineralisation rate of soil growing continuous wheat crops but underestimated mineralisation of soil in a clover-wheat rotation. For crops yielding <3 t/ha, the supply of N was mostly from mineralisation during crop growth and the contribution from mineral N accumulated before sowing was relatively small. For crops yielding >4 t/ha, thesupply of N was mostly from N present in the soil at the time of sowing. The implication is that for crops to achieve their water-limited yield, they must be supplied with an amount of N greater than can be expected from mineralisation during the growing season, either from fertiliser or from mineral N accumulated earlier.

Isoproturon movement and dissipation in undisturbed soil cores from a grassed buffer strip

Agronomie ◽  
2000 ◽  
Vol 20 (3) ◽  
pp. 297-307 ◽  
Author(s):  
Pierre Benoit ◽  
Enrique Barriuso ◽  
Philippe Vidon ◽  
Benoit Réal
Keyword(s):  
Soil Cores ◽  
Undisturbed Soil ◽  
Buffer Strip ◽  
Undisturbed Soil Cores

Relationship Between Soil Properties and Nitrogen Mineralization in Undisturbed Soil Cores from California Agroecosystems

2018 ◽  
Vol 50 (1) ◽  
pp. 77-92 ◽  
Author(s):  
Kenneth Miller ◽  
Brenna J. Aegerter ◽  
Nicholas E. Clark ◽  
Michelle Leinfelder-Miles ◽  
Eugene M. Miyao ◽  
...  
Keyword(s):  
Soil Properties ◽  
Nitrogen Mineralization ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Undisturbed Soil Cores

Effects of soil nitrogen status and rate of inoculation on the establishment of populations of Bradyrhizobium japonicum and on the nodulation of soybeans

1989 ◽  
Vol 40 (4) ◽  
pp. 753
Author(s):  
J Brockwell ◽  
RR Gault ◽  
LJ Morthorpe ◽  
MB Peoples ◽  
GL Turner ◽  
...  
Keyword(s):  
Glycine Max ◽  
Soil Nitrogen ◽  
Bradyrhizobium Japonicum ◽  
Clay Soil ◽  
Mineral Nitrogen ◽  
Soil Mineral ◽  
Soil Mineral Nitrogen ◽  
Nitrogen Status ◽  
Mineral N ◽  
Glycine Max L

Soybeans (Glycine max [L.] Merrill cv. Forrest) were grown under irrigation on a well-structured grey clay soil, previously free of Bradyrhizobium japonicum and containing relatively high levels of mineral N, at Trangie, N.S.W. There were two soil pretreatments, pre-cropped (which had the effect of reducing the level of mineral nitrogen in the soil) and pre-fallowed, and four rates of inoculation (B. japonicum CB 1809 - nil, 0.01 X, 1.OX [=normal] and 100X).Mineral nitrogen (0-10 cm) initially was higher in pre-fallowed soil than in pre-cropped soil (37.6 v. 18.5 mg N per kg). Depletion of mineral nitrogen occurred more rapidly in pre-fallowed treatments, so that, 7 days after harvest, mineral-N in pre-cropped soil was significantly higher than in pre-fallowed soil (14.4 v. 10.6 mg per kg).With high levels of soil mineral nitrogen, colonization of seedling rhizospheres by rhizobia and plant nodulation were diminished. These effects were ameliorated but not eliminated by increased rates of inoculation. The development of the symbiosis was also impeded by lower rates of inoculation (0.01 X, 1.OX).

Three-Dimensional Quantification of Macropore Networks in Undisturbed Soil Cores

1999 ◽  
Vol 63 (6) ◽  
pp. 1530-1543 ◽  
Author(s):  
Johan Perret ◽  
S. O. Prasher ◽  
A. Kantzas ◽  
C. Langford
Keyword(s):  
Three Dimensional ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Undisturbed Soil Cores

scholarly journals Estimating the van Genuchten retention curve parameters of undisturbed soil from a single upward infiltration measurement

Soil Research ◽  
2017 ◽  
Vol 55 (7) ◽  
pp. 682 ◽  
Author(s):  
D. Moret-Fernández ◽  
C. Peña-Sancho ◽  
B. Latorre ◽  
Y. Pueyo ◽  
M. V. López
Keyword(s):  
Water Retention ◽  
Time Domain Reflectometry ◽  
Soil Samples ◽  
Water Retention Curve ◽  
Internal Diameter ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Retention Curve ◽  
Loam Soil ◽  
Undisturbed Soil Cores

Estimation of the soil–water retention curve, θ(h), on undisturbed soil samples is of paramount importance to characterise the hydraulic behaviour of soils. Although a method of determining parameters of the water retention curve (α, a scale parameter inversely proportional to mean pore diameter and n, a measure of pore size distribution) from saturated hydraulic conductivity (Ks), sorptivity (S) and the β parameter, using S and β calculated from the inverse analysis of upward infiltration (UI) has been satisfactorily applied to sieved soil samples, its applicability to undisturbed soils has not been tested. The aim of the present study was to show that the method can be applied to undisturbed soil cores representing a range of textures and structures. Undisturbed soil cores were collected using stainless steel cylinders (5cm internal diameter×5cm high) from structured soils located in two different places: (1) an agricultural loam soil under conventional, reduced and no tillage systems; and (2) a loam soil under grazed and ungrazed natural shrubland. The α and n values estimated for the different soils using the UI method were compared with those calculated using time domain reflectometry (TDR) pressure cells (PC) for pressure heads of –0.5, –1.5, –3, –5, –10 and –50kPa. To compare the two methods, α values measured with UI were calculated to the drying branch of θ(h). For each treatment, three replicates of UI and PC calculations were performed. The results showed that the 5-cm high cylinders used in all experiments provided accurate estimates of S and β. Overall, the α and n values estimated with UI were larger than those measured with PC. These differences could be attributed, in part, to limitations of the PC method. On average, the n values calculated from the optimised S and β data were 5% larger than those obtained with PC. A relationship with a slope close to 1 fitted the n values estimated using both methods (nPC=0.73 nUI+0.49; R2=0.78, P<0.05). The results show that the UI method is a promising technique to estimate the hydraulic properties of undisturbed soil samples.

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