Straw is an agricultural crop residue readily available in many parts of the country, but care should be taken to avoid straw with harmful herbicide residues. It is ploughed in or composted and then worked in. There appears to be no advantage in composting if allowance is made for the demand on nitrogen by soil bacteria. About 6 kg of nitrogen fertilizer needs to be added for each tonne of straw for composting to preventing soil robbing (see p325). Chopping the straw facilitates its incorporation and while not decomposed it can open up soils. On decomposition it yields very little nutrient for plant use, but makes an important contribution to maintaining soil humus levels. Straw bales suitably composted on site are the basis of producing an open growing medium for cucumbers.
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