Trading Straw for Farmyard Manure – Calculating Relative Values for a Fair Exchange

Farmers may have sold straw in the swath this season or intend to trade baled straw for farmyard manure (FYM) over the coming months. For many arable and livestock farmers operating in close proximity to each other, it makes sense to come to an arrangement whereby straw is traded for FYM. Understanding the nutrient value of both straw and FYM in terms of nutrients removed and added back helps to form the basis of a fair exchange that benefits both parties. 

The table below shows how the nutritive values may be calculated using established data for nitrogen phosphate and potassium content per ton of straw and FYM respectively, and applying   current prices for bought in inorganic fertilisers.  

Where straw has been made available in the row at deemed market value, for example £60/acre and then making best estimates of straw yield, in this example, 1.6 tons per acre, it’s possible to equate the relative quantity of manure to exchange, as shown below:   

In this worked example 4 tons of FYM exchanged for every ton of straw seems appropriate including a notional value for organic matter addition. The ratio will of course vary relative to fertiliser prices, straw yield and seasonal straw values but the same principles apply. Further adjustments can be accounted for to reflect the cost to either party should they incur the baling costs and/or relative costs associated with haulage of the two outputs.