Predicting Temperatures of Bare and Residue Covered Soils With and Without a Corn Crop

Frequently the soil heat transfer is considered as a one‐dimensional (vertical) process which may be described by the differential equation (DE) of soil heat flow. Regarding the upper boundary, equations for bare and cropped fields are developed by means of data of Kiel and Michigan. For the lower boundary a theoretical and an empirical equation are given. The soil heat conductivity was estimated by the formulas of McInnes (1981). Equations are proposed for estimating the clay and quartz contents which are needed in these formulas. The convective term in the differential equation (DE) may be omitted without significant loss of precision. For the SALUS model in which the two upper layers are 2 resp. 5 cm thick a simple approximative solution for these two layers is given. The temperatures of the deeper layers are calculated by the DE for which in this case only two time steps per day are necessary. This yields short computing times.

Section: Upper Boundarysupporting

confidence: 82%

“…1-3). With the model of GUPTA et al (1981) a similar fitting could only be achieved by the input of a great number of additional measured data. Fig.…”

Section: Lower Boundarymentioning

confidence: 99%

Soil Temperature Model for CERES and Similar Crop Models

Hoffmann

Beinhauer

Dadoun

1993

“…But, they have rather large direct effects on rate and direction of root growth and, indirect effects on root morphology through effects on N mineralization and nitrification (see for example BLACKLOW 1972, ONDERDONK and KETCHESON 1973, and GLIEMEROTH 1953. Models such as that of GUPTA et al's (1981) can predict relative effects of tillage and residue management on soil-TEI. And, it is this man-…”

Section: General Observationsmentioning

confidence: 99%

Effect of Thermal Energy Intensity on Time and Rate of Nitrogen Accumulation by Maize (Zea mays L.)¹

Olness

Benoit

Sickle

et al. 1990

The effect of thermal energy intensity (TEI) on the rate of nitrogen (N) accumulation by maize from a Hamerly clay loam soil (Aerie Calciaquoll) was examined with and without supplemental irrigation. Soil‐ and air‐TEI expressed as cumulative growing degree days (GDD) was determined from hourly temperature measurements taken within each plot at soil depths of 0.05‐, 0.15‐, and 0.3‐m and at a height of 1.2‐m above ground surface. A daily mean TEI (GDD per day) was calculated for each growth period. Estimates of time coefficient(s), k, in uni‐ and diphasic tanhfk(time)] functions, plotted against mean TEI for the periods; 1) planting to emergence, 2) emergence to eighth leaf, 3) eighth leaf to time(s) of maximum N accumulation rate, (t0), 4) planting to t0, 5) emergence to t0, 6) first diphasic maximum accumulation rate (t01) to 50 % silking, and 7) silking to second diphasic maximum accumulation rate t02 showed several linear relationships. Uniphasic time coefficients were modelled as functions of air‐TEI. The first diphasic time coefficient, k, was modelled as a function of pre‐ and post‐emergent soil‐TEI. Attempts to model k2, the second time coefficient of the diphasic model were unsuccessful; however, this time coefficient was linearly related to TEI for the growth period ‘t01 to 50 % silking’ and curvilinearly related to k1. Zusammenfassung Der Einfluß thermaler Energieintensität auf Zeit und Rate der Stickstoffakkumulation bei Mais (Zea mays L.) Der Einfluß der thermalen Energieintensität (TEI) auf die Rate der Stickstoffakkumulation (N) bei Mais auf einem Hamerly ton‐lehmigen Boden (aerie calciaquoll) wurde mit und ohne zusätzliche Bewässerung untersucht. Boden‐und Luft‐TEI, ausgedrückt als kumulative Wachstumstage (GDD), wurden aus stündli‐chen Temperaturmessungen, die innerhalb der Parzellen in Bodentiefen von 0,05, 0,15 und 0,3 m und in Höhen von 1,2 m über dem Grund ermittelt wurden, bestimmt. Eine tägli‐che mittlere TEI (GDD/Tag) wurde für jede Wachstumsperiode kalkuliert. Die Ermittlungen der Zeitkoeffizienten, k, in ein‐ und zwei‐phasigen tanh[k(Zeit)]‐Funktionen wurden ge‐gen die mittlere TEI für die Perioden aufgetra‐gen; 1) Pflanzzeit bis Auflaufen, 2) Auflaufen bis 8‐Blattstadium, 3) 8‐Blattstadium bis zum Zeitpunkt der Maximal‐N‐Akkumulationsrate (t0), 4) Pflanzzeit bis t0, 5) Auflaufen bis t0, 6) erste zweiphasige Maximalakkumulationsrate (t01) bis 50 % Seidenauswurf und 7) Seidenaus‐wurf bis zur zweiten diphasischen Maximum‐akkumulationsrate t02 zeigten zahlreiche linea‐re Beziehungen. Die einphasigen Zeitkoeffizienten wurden als Modelle der Funktionen der Luft‐TEI dargestellt. Der erste zweiphasige Zeitkoeffizient, k1; wurde als Funktion der Vor‐ und Nachauflaufphase der Boden‐TEI behandelt. Versuche Modelle k2, der zweite Zeitkoeffizient für das diphasische Modell, waren nicht erfolgreich; allerdings war der Zeitkoeffizient linear bezogen auf TEI für die Wachstumsperiode t01 bis 50 % Seidenauswurf und kurvenlinear bezogen zu k1.

“…Grop residues left on the soil surface intercept and reflect incident radiation. Maintaining crop residues on the soil surface usually cause only a 2 to 3 °G temperature reduction in temperate region soils (GUPTA et al 1981, DO-RAN et al 1984); but, this can result in a near exponential change in root growth rate (BLACK-Low 1972).…”

Section: Introductionmentioning

confidence: 99%

Effect of Post‐Planting Residue Applications and Tillage on Nitrogen Accumulation and Partitioningin Maize (Zea mays L.)

Olness

1992

Effects of a tillage‐surface crop residue combination on nitrogen (N) accumulation by maize were examined using a replicated field experiment. Crop residues, < 70 % surface cover, were applied a few days aftei planting conventional‐ and ridge‐tillage treatments. With < 30 % surface cover, total accumulated‐N decreased from about 4 to 2 g plant−1 as the plant population density (PPD) increased from 4 to 7 plants m−2 With < 70 % surface cover, total N accumulated averaged about 3 g plant−1 over the PPD range of 4 to / plants m−1. At a PPD of about 5.5 plants m−2, equal amounts of N were accumulated by plants in al treatments. Nitrogen accumulation was periodically monitored and fitted to a diphasic tanh(k[time]) model About 1.8 to 2.6 g of N and about 0.70 to 1.4 g of N were accumulated before and after anthesis respectively. Maximum N accumulation rates averaged about 92 and 60 mg plant−1 day−1 during vegetativt and reproductive growth‐stages, respectively. Total N accumulation during the vegetative growth‐stag declined exponentially as PPD increased; this may reflect a crop demand‐soil supply relationship.