Page 101 - Nutrient Management Planning Guide

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Soil Sampling

Realistic yield goals: • A realistic yield goal is one that is achievable for a crop grown in a given area under a particular management system. Yield goals must take into consideration previous year’s crop, current and predicted moisture conditions, crop varieties, and time of year.

Previous crop: • This is particularly important if the previous crop was a legume or if the field was fallowed. Soil available N levels after fallow are generally higher and should be reflected in the soil analysis results. Legume residues will also provide N to subsequent crops; however, this N will not be detected in a standard soil analysis but will factor into fertility recommendations made by the lab.

Irrigated versus non-irrigated land: • Productivity (i.e., potential yield) and fertility recommendations will be higher for irrigated crops.

Residue management: • Crop residues have implications for nutrient availability to

subsequent crops. Cereal and oilseed residues will immobilize nutrients reducing availability for the immediate needs of subsequent crops. Fertilizer recommendations are lower when straw is baled and removed than when it is spread.

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Realistic yield goals may be estimated from historical yields, seed providers, regional variety trials, provincial averages, agronomists or service providers, specialists at the Ag-Info Centre, county offices or regional applied research associations.

Manure and fertilizer application history: • When making fertility recommendations, labs will consider previous nutrient applications (type or rates). When soil samples are taken immediately following manure or fertilizer application, some nutrients (e.g., NH

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+ ) will not show up in standard soil analysis results. Likewise, organic nutrients from previous manure applications will become available gradually during the growing season and will not be reflected in test results. Without the nutrient application history, fertility recommendations may be inflated.

Moisture conditions: • Yield response is closely tied to moisture conditions. By reporting this information to the lab, fertility recommendations will be adjusted accordingly.