Maize Root Distribution between Phosphorus‐Fertilized and Unfertilized Soil

Abstract

Placement of P in a fraction of the soil volume stimulates root growth in the P‐fertilized soil. Previous research on the degree of root proliferation as related to the proportion of soil fertilized with P was conducted with soils containing similar low levels of initial resin‐exchangeable P, Csi, and hence did not evaluate the influence of Csi on the degree of root proliferation in a P‐fertilized fraction of the soil. These measurements were made as part of research to determine the fractional volume of soil to fertilize with P to maximize P uptake. The objective of this research was to investigate the influence of initial soil Csi value and rate of P added on root distribution between P‐fertilized and unfertilized soil when the P‐fertilized volume is constant. Pot experiments were conducted in a controlled‐climate facility where maize (Zea mays L.) was grown on three soils varying in Csi levels and with three rates of applied P, from 50 to 300 mg kg−1, added to 0.20 of the volume of each soil. Root density, cm cm−3, in the P‐fertilized soil volume, RDF, and a comparable 0.20 volume of unfertilized soil, RDU, was measured and compared with Csi in the P‐fertilized soil, CsiF, and in the unfertilized soil, CsiU. There was a curvilinear relation between CsiF/CsiU and RDF/ROU that was described by the equation y = 1.20 + 2.74 log x (r2 = 0.97), where y is RDF/RDU and x is CsiF/CsiU. Hence, as soil Csi level increased, RDF/RDU decreased, and as rate of P applied increased, RDF/RDU increased. The relation between CsiF/CsiU and RDF/RDU can be used to predict root growth rates to use in the fertilized and unfertilized soil when using a mechanistic nutrient‐uptake model to calculate the effect of P placement on P uptake.

Densidade do solo, atributos químicos e sistema radicular do milho afetados pelo pastejo e manejo do solo

“…Concordando com o observado por Anghinoni & Barber (1980), Zhang & Barber (1992) e Klepker & Anghinoni (1995), as raízes de milho podem apresentar crescimento diferenciado na direção da concentração de nutrientes no solo, principalmente de fósforo. A densidade de raízes correlacionou-se positivamente com o atributo físico porosidade total, nas profundidades de 10-15 e 30-35 cm.…”

Características químicas de solo e rendimento de massa seca de milho em função do método de aplicação de fosfatos, em dois níveis de acidez

“…A boa eficiência do P aplicado sobre a superfície, provavelmente, está relacionada com o maior incremento na concentração de P na solução do solo nessa região, em conseqüência do aumento na percentagem de saturação dos sítios de adsorção, resultante da redução do contato do fertilizante com o solo. A localização de P, no entanto, diminui o volume de solo fertilizado com o qual as raízes entram em contato, o que pode prejudicar a absorção do nutriente (Zhang & Barber, 1992), especialmente em períodos de déficit hídrico.…”

Determination of Optimum Rate and Growth Stage for Foliar‐Applied Phosphorus in Corn

“…The banded P usually increased early crop growth more than the broadcast placement because of increased plant uptake (Barber 1984;Mallarino and Rueber 2001;Rehm et al 1998;Eghball, Sander, and Skop 1990). In corn (Zea mays L.), Zhang and Barber (1992) studied the effect of P placement on P uptake and reported similar results. It is important to improve P use of the plant by investigating alternative methods, including foliar application.…”