Browsing by Author "Amoah, Samuel"

Tiivistelmä/Referat – Abstract Biochars, made from biomass heated in limited oxygen, have been suggested as a sustainable means of increasing crop productivity. Two of the most commonly reported benefits of biochars are improved soil water availability and nutrient status, due of which also yield increases have been reported. Most studies so far have focused on subtropical soils that are low in initial carbon content, and cereals have been the main crops studied. There is also lack of knowledge of the effects of biochar in longer term than five years on the yield formation of grain legumes like peas. A long-term field experiment was conducted in Helsinki, Finland to investigate the effects of softwood biochar on the soil properties and on the yield formation of peas. Three levels of biochar rates were used: 0 ton/ha, 5 ton/ha and 10 ton/ha in conjunction with 3 NPK fertilizer levels of 30, 65, and 100 percent of the recommended levels. The addition of biochar was tied to slightly elevated levels of soil moisture at the upper soil layers (0 – 18 cm). This increase was however not significant (p > 0.05). Changes in biochar porosity over the years may have led to decreased water holding capacity of the soil and hence low moisture content. The soil nutrient status was also not significantly affected by biochar additions, except for sulphur levels which recorded a marginal significance of p < 0.1. Changes in biochar properties over time could also be responsible for the lack of effects on soil nutrients. The soil used was relatively fertile (3.5 % C), hence the effects of biochar were insignificant. Fertilizer effects were also not significant, except for significant levels of such nutrient as P, Ca, P and S. The lack of fertilizer effects could be due to the relatively fertile nature of the Luvic Stagnosol soil. The lack of effects of biochar on soil properties resulted in non-significant results for yield components of peas. The relatively dry weather during the growing season could also be responsible for the vast lack of significance recorded.