Comparisons of crop yields using semi-organic and inorganic fertilizers
A series of experiments is described in which a semi-organic fertilizer is compared to the more widely used inorganic type. A semi-organic fertilizer contains a base of organic materials to which is added a mixture of inorganic salts to make up a suitable analysis. The results from three years field trials and certain greenhouse experiments are presented. Barley was used as the test crop in all experiments. Biomass production and nitrogen accumulation were studied in the field trials. In the field trials a greater stand density was produced using the semi-organic fertilizer as compared with an inorganic fertilizer and no-fertilizer treatment. This difference was evident from early in the season and was therefore attributed to relative success in germination and/or establishment. A high salt concentration in the soil water surrounding seeds has been shown to reduce the rate and final percentage germination for a wide variety of crops. The superior stand density produced on the semi-organic treatment was probably due to the lower osmotic effect produced by that fertilizer. The results of the greenhouse experiments supported this hypothesis. Field and greenhouse experiments were not analogous with respect to the emergence observed on the no fertilizer treatment. The pattern of nitrogen uptake was different on the two fertilizer treatments. Proportionally more nitrogen was absorbed later in the season by plants growing on'the semi-organic treatment. This led to a greater nitrogen content per head on the semi-organic treatment. Although there were significantly more heads per unit area on the semi-organic treatment there was no difference in the dry weight per head, this could be due to prolonged photosynthesis in the heads on this treatment. Total biomass production was similar on the two fertilized treatments but proportionally more of the weight was in the heads on the semi-organic treatment. There was a strong negative correlation, later in the season, between plant density and a) dry weight per plant and b) nitrogen content per plant on the inorganic fertilizer treatment but this was not so on the semi-organic fertilizer.