Effect of humic acid on the physical properties of a Haplohumult cultivated with wheat

Abstract

Considering the fragility of Ultisols subjected to intensive agricultural use, the present study aimed to evaluate the effect of humic acid on some physical properties of an Andic Haplohumult cultivated with wheat in the Araucanía Region, south of Chile. The treatments were a control without amendment (T0), application of humic acid (T1), and native forest (T2) in which the soil has not been altered for more than twenty years. Samples were taken at two depths (0-10 and 30-40 cm) with four replications, evaluating some physical properties one month after the amendment application and six months thereafter. Also, yield components for wheat were measured. As for the soil physical properties, in the short term the application of humic acid had positive effects on water retention, there was an increase in porosity, a decrease in bulk density and improved stability of macroaggregates in depth (30-40 cm), reaching levels similar to native site. There was also a higher biomass production and a 24% increase in wheat yield in the treatment with application of the amendment with respect to the control without amendment. This result is explained by an increase in number of grains per square meter, without changing the weight of the grain, with a higher amount of grains per spikes due to better soil condition.