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Control of Nutrient Mixing and Uptake by Irrigation Frequency and Relative Humidity
Author(s) -
Kargbo D.,
Skopp J.,
Knudsen D.
Publication year - 1991
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1991.00021962008300060018x
Subject(s) - soil water , udic moisture regime , nutrient , loam , chemistry , irrigation , water content , flux (metallurgy) , agronomy , field capacity , humidity , relative humidity , hydrology (agriculture) , zoology , soil science , environmental science , biology , geology , physics , geotechnical engineering , organic chemistry , thermodynamics
The distribution of nutrients and water between mobile and immobile pores should influence nutrient uptake. The distribution can be regulated through control of the water‐filled pore space. This research was conducted to determine the effect of varying soil‐water content and water uptake upon nutrient uptake. Corn ( Zea mays L.) was grown in a growth chamber for 2 wk at 35 or 55% relative humidity (RH). Three soils [Boelus LS, 5% slope (sandy over loamy, mixed, mesic Udic Haplustoll); Boelus LS, 2% slope; and Plano Soil (fine‐silty, mixed, thermic Typic Haplustolf)] were watered to field capacity (θ max ). Plants on each soil were allowed to extract water to one of three minimal levels (θ min1 , θ min2 , θ min3 ) before rewatering. After harvest, P and K content and other root and leaf parameters were determined. The values of θ min were chosen so that, for each soil, the three values ensured no low‐water stress. Effective diffusion coefficients were determined for the three Increased O min for a soil required for frequent watering, which led to greater mixing of solutes between pores. At 55% RH, no water treatment significantly affected P and K flux, despite significant differences in diffusion coefficients. At 35% RH, however, phosphate flux to roots increased as θ min increased. The significant increase of phosphate flux with more frequent watering at low RH suggests that plant uptake is affected by soil physical processes other than simple diffusion and convection to individual roots. More frequent watering results in greater mixing of solute between pores containing mobile and immobile water and, consequently, greater uptake.