Maize (Zea mays L.) is an important cereal crop not only in the world but more specifically in South Africa. Therefore, understanding maizeâs nutrient requirement becomes an importance factor especially during the vegetative growth period. Nitrogen (N) and phosphorus (P) are reported to be two essential nutrients for both accelerated vegetative growth and maximum yield. Addition of these two plant nutrients should include consideration of both form and total nutrient concentration, since these two factors determine availability and accessibility.
In order to evaluate the response of maize to P sources and P application rates as well as N sources a glasshouse experiment was conducted in 40.5 L pots filled with a dark brown sandy-loam topsoil pertaining a medium soil pH of 5.5. Treatments consisted of three main factor treatments viz. N source (urea and limestone ammonium nitrate - LAN), P source (monoammonium phosphate - MAP, nitrophosphate - NP and ammonium polyphosphate - APP) and P application rate (0, 10, 20, 30 and 40 kg P ha-1). Treatments combinations were replicated three times and independently subjected to a randomized complete block design with a factorial combination. The experiment was repeated on two planting dates. Treatments and treatment combinations were band applied to dry soil in a single 0.34 m line, 50 mm below and 50 mm away from the maize seeds; which were planted with a between row spacing of 0.91 m, 50 mm below the soil surface. After planting the soil was watered and maintained at field capacity for a duration of five weeks after emergence. The aerial parameters of three plants per pot were measured on a weekly basis following emergence while the subsoil parameters were taken at the end of the five week vegetative growing period.
Both aerial and subsoil parameters showed responses to nitrogen source; which was strongly reflected during both plantings. Plants treated with LAN yielded both greater aerial and subsoil measurements compared to urea, primarily ascribed to immediate availability after application in addition to ease in uptake. Both aerial and subsoil parameter response to phosphorus source and P application rate, though apparent throughout both plantings, was more prominent during the first planting. Monoammonium phosphate and NP (orthophosphate sources) yielded greater aerial measurements compared to that of the APP (polyphosphate source). Subsoil parameter results comparing phosphorus sources were inconsistent. Subsoil parameters of the fertilized zone were significantly greater with the use of MAP (orthophosphate), while APP (polyphosphate) yielded significant greater subsoil parameters within the unfertilized zone. Both aerial and subsoil parameter measurements taken either throughout or at the end of the vegetative growth period were overall significantly greater when P was applied at 40 kg P ha-1. Subsoil parameter response in and away from the fertilizer band was however inconsistent.
The aerial dry plant material was analyzed (Omnia Nutriology®) to evaluate the effect of the three main treatments on the quantitative nutrient concentration as well as the uptake thereof. Nutrient concentration and uptake was used to determine the synergistic or antagonistic effect of treatments or treatment combinations.
Nutrient concentration measurements were inconsistent for N source, however total uptake proved to be more efficient with the application of LAN compared to urea. Both nutrient concentration and uptake was greater with the application of both the orthophosphate sources (MAP and NP) compared to the polyphosphate source (APP). The 40 kg P ha-1 application yielded a synergistic response to the total uptake of S, N, P, Ca and B, while a synergistic nutrient concentration response was found with the control treatment for N, Mg, Cu and Zn nutrients. Nutrient uptake was also stimulated by an increasing rate of P.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-08212014-151728 |
| Date | 21 August 2014 |
| Creators | Coetzee, Pieter-Ernst |
| Contributors | Prof CC du Preez, Dr GM Ceronio |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-08212014-151728/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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