Page 56 - Nutrient Management Planning Guide

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Manure and Fertilizer as Sources of Nutrients and Potential Environmental Hazards

Important Terms

Table 2.3.1 Key Terms and Definitions

Term Definition

Crop Available or Available Nutrient

A nutrient in a chemical form accessible to plant roots or compounds likely to be converted to such forms during the growing season.

Inorganic Nutrients

Nutrients that are not bound to organic carbon. These nutrients can be readily absorbed and used by plants.

Organic Nutrients

A form of nutrient that is bound to organic carbon and cannot be readily absorbed and used by a plant. Organic nutrients require a physical or chemical conversion to an inorganic form prior to use.

Soil Organic Matter

Consists of living or dead plant material, organisms, products derived from microbial and animal metabolism and stabilized complex organic material called humus. As organic matter breaks down (mineralized) nutrients are released in a form that plants can use.

Pore Space

This is the ‘space’ between soil particles or the total space not occupied by soil particles in a bulk volume of soil.

Manure and fertilizers are important sources of nutrients for crop production in Alberta. However, improper management can negatively impact environmental quality and human health. One of the primary reasons for developing a NMP is to maximize the benefits of manure and fertilizer application, while minimizing environmental risk.

Manure and Fertilizer as Sources of Nutrients

Fertilizers and manure are important sources of nutrients for crop production. To maximize the benefits of both, it is important to recognize how they differ.

Fertilizer

Using commercial fertilizers is less complicated than using manure for several reasons:

The nutrient content of fertilizers is standardized •

and consistent. Manure, in contrast, can vary considerably in nutrient content creating difficulties for accurate nutrient applications. Fertilizers and soil test recommendations express •

nutrient content in the same way; percent N, P

2

O

5

, and K

2

O for nitrogen, phosphorus and potassium respectively. Manure values for these nutrients are expressed as percent total N, P and K. To avoid errors in calculating application rates, manure nutrient values must be converted to the same chemical form as reported in soil test recommendations (N, P

2

O

5

, and K

2

O). Fertilizers contain simple inorganic forms of •

nutrients that are readily available to plants. In contrast, manure contains organic and inorganic nutrient forms with varying plant availability. This makes it difficult to estimate nutrient availability from manure and appropriate manure application rates to meet nutrient demands in the year of application.