Lesson 23. Tilth and Its Characteristics

23.1 INTRODUCTION

The aim of tillage is to produce as good a soil condition or tilth as possible for crop establishment and initial shoot and root development. The term tilth is used to describe qualitative characteristics of a loose friable (mellow) and crumby condition of the soil favourable for crop production. When the soil is brought to such a condition ideal for crop growth it is called a seedbed and is said to be in good tilth. In other words, tilth is physical condition of soil resulting from tillage. The ideal seedbed is a soil in which porosity of the mineral solid matter provides an optimum balance between water holding and freely drained. The optimum balance appears to be the one in which capillary and non capillary pores are in equal proportion.

23.2 FACTORS INFLUENCING TILTH

Factors contributing to tilth are

1. Soil texture

2. Soil structure

3. Organic matter content and

4. Weather.

23.2.1 Soil texture

Texture is an inherent soil property which is difficult to modify, except to a very small scale. Agricultural significance of soil structure is related to its effect on porosity and permeability and on the surface area of the soil fraction.

23.2.2 Soil structure

Structure which indicates the way in which the individual mineral particles are arranged to form aggregates is important in determining soil tilth. The structure considered ideal for agriculture is crumb in which the aggregates are small, porous and relatively water stable.

23.2.3 Organic matter content

Soils with high organic matter cultivated at optimum soil moisture leads to crumb structure with aggregate stability. Exposure of soil surface to wetting and drying contributes to breakdown of large clods in heavy soils (self tillage) leading to loose surface with aggregates.

23.2.4 Weather

The development of soil structure is resulted from the complex interaction between weather, method of cultivation and soil organic matter content.

Last modified: Saturday, 3 August 2013, 6:30 AM