Tilth can refer to two things:

Tillage

Tillage

Tillage is the agricultural preparation of the soil by mechanical agitation of various types, such as digging, stirring, and overturning. Examples of human-powered tilling methods using hand tools include shovelling, picking, mattock work, hoeing, and raking...

 and a measure of the health of soil

Soil health

Soil health is an assessment of ability of a soil to meet its range of ecosystem functions as appropriate to its environment.- Aspects of soil health :The term soil health is used to assess the ability of a soil to:...

.

Good tilth is a term referring to soil that has the proper structure and nutrients to grow healthy crops. Soil in good tilth is loamy, nutrient-rich soil that can also be said to be friable because optimal soil has a mixture of sand, clay and organic matter that prevents severe compaction.