Attention to Spring Sampling Pays Off

Adapted by Deanne Meyer, UCCE Livestock Waste Management Specialist

It’s that time of the year - clocks are set forward and harvest is on top of us.  Remember to review your Sampling and Analysis Plan BEFORE crops are harvested and manure is land applied.  It’s critical to have good estimates of nutrients applied to crops and removed from fields.  The calculation used to determine nutrients applied to or removed in crops requires input of quantity and nutrient content.  

Precisely tracking quantity of material applied and documenting this is important.  Also, taking a representative sample, preserving it correctly (usually on ice or chilled) and delivering it to the laboratory near immediately (within 24 hours) is essential to receive useful and valid nutrient composition data. 

As a recap, you should have sampling protocols for solid and liquid manure, plant tissue, irrigation water, and soils.  Review your protocols and follow them.  Solid manure and plant tissue sample collection should rely on collecting many grab samples from the same source and mixing them thoroughly to subsample the composite sample.  Liquid manure samples should be collected directly into the container without overtopping.  The sample requires refrigeration between collection and delivery to the laboratory.  This type of sample should be delivered to the lab well under 24 hours after collection.  Irrigation water sources should be sampled into the container going to the lab. Like liquid manure, this sample should be placed on ice.  Soil samples need to be kept dry and be delivered to the laboratory soon after collection.

One composite sample of crop material should be taken from each field where manure was applied.  Liquid manure should be sampled quarterly when this source is used in irrigations.  Solid manure should be sampled twice annually.  Irrigation water sources need to be sampled annually during the irrigation season. Soil samples need to be taken on 20% of fields, annually.

A good representative sample is essential to closely track nutrient applications to and removals from fields.  The results from representative samples are critical for your Annual Reporting and equally as important to general crop management (nutrient application efficiencies). 

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