The effect of fertilizer type and application method, seed pelleting and simulated rainfall on brassica establishment and yield: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Agricultural Science with Honours at Lincoln University

Abstract

An experiment was conducted to determine the optimum fertilizer type for the establishment and yield of brassicas when seed was mixed with the fertilizer. Of the fertilizers commercially available, Cropmaster 20 treatments achieved significantly lower levels of establishment, achieving under half of the plant density of other fertilizer treatments after 30 days with 15% establishment of viable seed. The control gave highest initial rates of establishment over 30 days, but post emergence deaths were increased possibly due to increased plant competition. Lime reverted super was the highest yielding treatment and was significantly different to Cropmaster 20, but was no better than any of the other fertilizer treatments including the control. Phosphate based fertilizers also had significantly more plants/m² than nitrogen containing fertilizers. Individual plant weight remained unaffected and was more dependent on plant density. In a second experiment, the effect of broadcasting the fertilizer before drilling, and seed pelleting were investigated. Establishment was not improved by either of these treatments, with all plots averaging about 30 plants/m² after 30 days. None of the treatments had any significant effect on final yield or individual plant weight, including seed pelleting. Plants/m² was affected by treatments with drilled Cropmaster 20 treatments having significantly fewer plants/m² than broadcast treatments. Lime reverted and longlife treatments had significantly higher plant populations where fertilizer was drilled with the seed. A third pot experiment was conducted to investigate the effect of simulated rainfall at different stages after sowing brassica seed when mixed with fertilizer. With air dried soil and no rainfall after sowing, rates of-establishment were low, approximately 50% of viable seed at 30 days. This was further reduced by soluble fertilizers such as Cropmaster 20 to under 10% of viable seed thirty days after drilling. Simulated rainfall (25mm) two days sowing optimised germination and establishment with up to 96% of viable seed emerging in the lime reverted fertilizer treatments. Cropmaster 20 treatments were improved, but still remained substantially lower at 28% of viable seed. Simulated rainfall (25mm) at day ten caused a rapid increase in plant populations by day sixteen, indicating that seed remains viable at low soil moisture conditions in the absence of high concentrations of soluble salts. Populations were still increasing after thirty days when population counts ceased. Patterns of germination with different fertilizers types across simulated rainfall treatments were similar indicating that simulated rainfall did not improve individual fertilizer treatment establishment rates.