Effects of commercial chemical and microbiological products in soil on maize growth and yields

Abstract

A study was conducted under screenhouse and field conditions at Sokoine University of Agriculture to evaluate the effects of commercial chemical and microbiological products on growth and yields of SITUKA maize variety grown on an Ultisol soil. The study soil had medium organic matter, low available phosphorous (1.02 mg/kg) and very low extractable zinc (0.34 mg/kg) hence the soil was of medium fertility status and only moderately suitable for maize production. Commercial products evaluated were Teprosyn, P-solubilizers and N 2 -fixers, in each experiment using the randomized complete block design (RCBD) with three replications. Six treatments, namely: i.control (without commercial product and P- fertilizer), ii.commercial product alone at manufacturer’s recommended rate, iii.commercial product alone at double rate, iv.commercial product + 10 kg P ha -1 P-fertilizer, v.10 kg P ha -1 P-fertilizer and vi.20 kg P ha -1 P-fertilizer, were used. In the screenhouse, Teprosyn, P- solubilizers and N 2 -fixers did not result in significantly (P<0.05) different growth performance or biomass yields relative to those in the control. However, these products in combination with P-fertilizer (at half recommended rate) resulted in significant (P<0.05) increase in growth parameters and biomass yields. Teprosyn increased biomass yields from 0.96 g/plant (Control) to 1.89 g/plant (K 2 HPO 4 at 20 kg P ha -1 ), P-solubilizers from 1.01 g/plant (Control) to 1.71 g/plant (K 2 HPO 4 at 20 kg P ha -1 ) and N 2 -fixers from 0.95 g/plant (Control) to 2.19 g/plant (K 2 HPO 4 at 20 kg P ha -1 ). Under field experimentation, Teprosyn, P-solubilizers and N 2 -fixers had no significant (P<0.05) effect on maize growth performance. Only the P-solubilizers, either alone or in combination with P-fertilizer, produced significantly (P<0.05) higher grain yields than the control increasing grain yields from 2.04 t ha -1 (Control) to 3.53 t ha -1 (YaraMila Cereal at 20 kg P ha -1 ). It is recommended that Tanzania fertilizer regulatory authority should require manufactures to improve the quality standards of before the commercial products are accepted in the country and they should further be tested in other P-deficient soils.