Phosphorus Utilization by Flax, Wheat, Rape, and Buckwheat from a Band or Pellet-like Application. I. Reaction Zone Root Proliferation1
- W. M. Strong and
- R. J. Soper2
To explain the large variability among crops in their utilization of P from band or pellet-like applications, the recovery of 33P-labelled dicalcium phosphate dihydrate (DCPD) from a simulated phosphate fertilizer reaction zone was studied in a pot experiment with four crops, flax (Linum usitatissimum L., cv. Redwood), wheat (Tri. ticum vulgate L., cv. ‘Manitou’), rape (Brassica napus cv. ‘Tanka’), and buckwheat (Fagopyrum eseutentum Moench). Attention was focused on the portion of the root system which feeds on the applied P. Reaction zone root development was quantified by confining the spread of applied P to a small, easily recoverable portion of the soil mass in the pot. Root systems of the four crops proliferated within this simulated phosphate reaction zone, each to a varying degree. In increasing order of reaction zone root proliferation, the crops ranked as follows: flax, wheat, buckwheat, and rape.
The influence of root development within the fertilizer reaction zone on applied P utilization was assessed for these four crops by comparing crop utilization of applied P from two systems each fertilized with a simulated fertilizer reaction zone containing 32P.labelled DCPD. In one system the reaction zone was positioned at the center of the soil mass within the pot. In the other, a greater opportunity was afforded the root system to develop within the reaction zone by so positioning the reaction zone that the entire root mass passed through it. Recovery of labelled P from these contrasting pot shapes indicated that the proportion of the root system which feeds within the reaction zone as well as the opportunity given it to absorb applied P has direct bearing on crop recovery of band applied phosphatic fertilizer.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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