Influence of humic acid applications on modulus of rupture, aggregate stability, electrical conductivity, carbon and nitrogen content of a crusting problem soil

İ Gümüş,C Şeker

doi:10.5194/se-6-1231-2015

Abstract

Abstract. Soil structure is often said to be the key to soil productivity since a fertile soil, with desirable soil structure and adequate moisture supply, constitutes a productive soil. Soil structure influences soil water movement and retention, erosion, crusting, nutrient recycling, root penetration and crop yield. The objective of this work is to study humic acid (HA) application on some physical and chemical properties in weakly structured soils. The approach involved establishing a plot experiment in laboratory conditions. Different rates of HA (control, 0.5, 1, 2 and 4 %) were applied to soil during three incubation periods (21, 42 and 62 days). At the end of the each incubation period, the changes in physicochemical properties were measured. Generally, HA addition increased electrical conductivity values during all incubation periods. HA applications decreased soil modulus of rupture. Application of HA at the rate of 4 % significantly increased soil organic carbon contents. HA applications at the rate of 4 % significantly increased both mean soil total nitrogen content and aggregate stability after three incubation periods (p < 0.05). Therefore, HA has the potential to improve the structure of soil in the short term.

Highlights

The widespread use of unsuitable and unsustainable production techniques in agricultural systems has resulted in extensive deterioration of soil quality and reductions in soil organic matter content and crop production (Verhulst et al, 2010; Martinez-Blanco et al, 2011)
The soil sample used in this study has problems such as insufficient seedling emergency, low aggregate stability and crusting problems (Bal et al, 2011) Composited soil samples were taken from a problematic plot in the Agricultural Faculty of Selçuk University experiment station (0–20 cm soil depth) near the Konya Sarıcalar village located in Central Anatolia, Turkey (38◦06 N, 32◦36 E; 1010 m)
Yılmaz (2011) reported that biological and physicochemical properties of organic materials can play roles in mineralization of nitrogen from organic materials during incubation periods. The results of this laboratory study indicate that humic acid applications can improve the stability of structurally soils

Summary

Introduction

The widespread use of unsuitable and unsustainable production techniques in agricultural systems has resulted in extensive deterioration of soil quality and reductions in soil organic matter content and crop production (Verhulst et al, 2010; Martinez-Blanco et al, 2011). Soil organic matter plays an essential role in nutrient (N, P, S, K) cycles, soil stability and the ecological and environmental aspects of sustainability of soil fertility (Garcıa-Gil et al, 2004). Turkish soils generally have low organic matter levels and are commonly treated with mineral fertilizers that may improve yield in the short term but do not enhance the physical properties of the soil and result in soil degradation over the longer term. In many regions in Turkey, especially in Central Anatolia, the organic matter content of soils has fallen below 2 or 1 % (Seker and Karakaplan, 1999)

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