Sentence:  When surplus <WSD>land</WSD> is not expensive to buy or to keep up , it is usually better to buy it than to buy so small an acreage that the development of adjoining properties might impair the residential value of the farm . 
Meaning of the word marked with <WSD> tags:  material in the top layer of the surface of the earth in which plants can grow (especially with reference to its quality or use)