Principle Component and Hierarchical Cluster Analysis of Soil Properties following Biochar Incorporation

Abstract

Soil degradation has become a major problem in agricultural systems worldwide. It is thus critical to develop new, effective soil amendments to improve soil properties. In this study, soil incubation experiments were conducted to investigate the effects of biochar on soil chemical and biochemical properties combined with the statistical techniques of principal component analysis and hierarchical cluster analysis. Biochars derived from four types of feedstocks were added to Psammaquent, Plinthudult, and Paleudalf soils at rates of 1 and 3% for incubation. After 180 d, biochars increased the soil total C, cation exchange capacity, exchangeable base cations, and pH and decreased the exchangeable Al, while the changes in exchangeable inorganic N and the soil microbial biomass were complicated in different soils and biochars. The effect of biochars on soil properties were: swine manure biochar > pineapple [Ananas comosus (L.) Merr.] peel biochar = rape (Brassica campestris L.) straw biochar > reed [Phragmites australis (Cav.) Trin. ex Steud.] straw biochar. The most susceptible parameters influenced by biochar addition in the Psammaquent soil were acidity-related properties, whereas it was both N species and acidity-related properties for the Plinthudult and Paleudalf soils. The higher incorporation rate caused large changes in soil properties and the overall properties of the Psammaquent soil were more easily influenced by biochars than the Plinthudult and Paleudalf soils. In conclusion, biochar appeared more appropriate to correct the acidity in the Psammaquent soil, whereas it also affected N species changes in the Plinthudult and Paleudalf soils. The swine manure biochar had the greatest amelioration effect on the properties of the three soils.