HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Giskin, M. Articles by Kafkafi, U. Search for Related Content PubMed Articles by Giskin, M. Articles by Kafkafi, U. Agricola Articles by Giskin, M. Articles by Kafkafi, U.

Crop Response to Phosphate Fertilization and to Residual Phosphate Levels: III. Greenhouse Experiment¹

The greenhouse experiment was performed as a supplemerit to the field experiments described elsewhere, having in view that crop sequence is faster and that yield response to fertilizers is more likely to be found in such experiments than in the field. The aims of the experiment were to evaluate the build-up or depletion, during continuous cropping, of "available" phosphorus in soils with varying residual phosphate levels and to determine the contribution to yield of freshly applied and residual phosphates.

The pot experiment, with three soils and seven consecutive crops, received super-phosphate in amounts of 0, 19.4, 58.2, and 174.6 ppm P/3 kg soil. After removal of the third crop each of the four initial treatments was divided into four subtreatment groups. Rates of fertilization remained similar.

A linearity of relationships was found between P-uptake and total amount of fertilizer applied, dry matter yield and P extracted by NaHCO₃ or water. For all three soils the freshly applied phosphate was more readily "available" than the residual phosphate but there was a decrease in dependence of yield response to freshly applied phosphate when the soil residual phosphate levels were high. In the Neve Yaar soil, the freshly added phosphate, expressed as ppm P in soil, produced roughly the same yield as an equivalent amount of NaHCO₃-extractable P. Whereas, in the Lachish soil, approximately two to three times more of fresh P has to be applied in order to approximate the same yield level of NaHCO₃-extractable P. This indicates a lower or slower fixation of phosphorus in the Neve Yaar soil and concurs with results found in the field experiments. Thus some quantitative relationship between plant response to freshly applied and residual phosphate was found which was not capable of being calculated from data of the field experiments.

Key Words: Yield curves • Correlations

² Technicion-Israel Institute of Technology, Haifa, Israel.

³ Technion-Israel Institute of Technology (present address: Volcani Institute of Agricultural Research, Neve Yaar, Israel).

⁴ Volcani Institute of Agricultural Research, Beth Dagan, Israel.

Received for publication September 21, 1971.