Methods of Applying Fertilizer Chapter 7

What to consider when selecting an application method. Rooting characteristic of the crop to be planted. Crop demand for various nutrients at different stages of growth. Physical & chemical characteristics of the soil. Physical & chemical characteristics of the fertilizer material to be applied.

Availability of moisture. Type of irrigation system used if irrigation is the only, or major, source of water. Frequency and rate of irrigation water to be applied.

Pre-Plant Applications Broadcast – distributing over the top of the soil. Dry or liquid form. May be mechanically worked into the soil or incorporated by rainfall or irrigation.

Drop Spreader Simple Fertilizer spreader – inverted triangle-shaped hopper mounted between two wheels. -’s = small hopper size limits the load capacity & field size it can be used on. +’s = small size lends itself well to vineyards and orchards.

Spinning-disc spreader A small bulk spreader pulled by a tractor or truck. Uses horizontal spinning disc to broadcast fertilizer. 20’ – 40’ swath -’s easy to have skips or overlaps of fertilizer.

Self-propelled spreader A large bin mounted on a large truck or a special 3 or 4 wheel vehicle equipped with floatation tires ( reduce soil compaction) Can have simple horizontal-spinning-disc to air-flow applications Air-flow applicators have the capability to apply more than one fertilizer material at the same time.

Liquid Spreader

Tank, Pressure gauge, Regulator, Pump, Pipes, Hoses, Fittings, Nozzles, and a boom. Can be mounted on a truck, on a flotation vehicle or trailer, or directly on a tractor

Organic Spreaders Similar to a spinning disc spreader. Normal to apply 5 – 20 tons per acre. Poultry waste is at a lower rate.

Pre-Plant Applications - Injection Injection refers to placing fertilizers below to soil surface. All fertilizer that can be broadcasted on the soil can also be injected.

How does injection take place? Drop pipes for liquids. Flexible tubes for dries. Channels are made by knives or shank openers mounted to the tool bar. This is best done after the soil has been plowed, disced or furrowed out and the soil is loose.

Advantages of injections. Eliminates N gaseous losses. Reduces fertilizer losses caused by rain or wind erosion. Places the fertilizer directly in the root zone.

Disadvantages of injection. Power requirements are greater. Some specialized equipment is required for some types of fertilizer. (Anhydrous ammonia) May disrupt the integrity of the beds. Liquids are harder to apply than dry.

Applications at Planting Subsurface Banding (pop-up application) Appling fertilizer directly with the seed. Grain crops do well with this. Note** use low rates of starter fertilizers Look at chart 7-1 found on page 168.

Surface Banding Liquid fertilizers being applied to the soil surface directly above the seed. Sprinkler or rainfall need to move fertilizer down. Also used as an anti-crust. (acid serves to dissolve calcium carbonate crusts that impede crop emergence.)

Post-Emergence Application Sidedressing – refers to placement of fertilizer beside crop rows & may be combined with cultivation. Both liquid and dry can be used.

Topdressing Appling fertilizer to the soil surface after the crop emergence. The same equipment is used in the pre- plant broadcast applications

Water-Run Application Savings in time, labor, equipment, & fuel cost. May be pre-plant or post-emergence. Disadvantage to this type of application is uniformity of distribution and run-off water containing fertilizer.

Irrigation – Open Systems Ditches (lined or unlined) Gated pipe (used for furrow or flood irrigation) Both dry & liquid fertilizers can be used.

Irrigation – Open Systems High-pressure center pivot, linear, and solid-set sprinkler systems. Low pressure drip, mist, & micro-sprinkler irrigation systems. Not all dry & liquid fertilizers are suitable for application in closed systems.

Examples Aqua ammonia & anhydrous ammonia due to the precipitates that may be formed if irrigation water high in calcium content. Plugging is a main problem in low pressure systems.

Foliar Application Supplying nutrients during periods of peak demand when an immediate response is desired. Supplying certain nutrients, such as zinc, when soil or crop conditions are conductive to root uptake. Allowing precise timing of nutrient application related to the quality characteristics of the crop being grown.

Reducing nitrate leaching in certain cropping systems. Providing a source of nutrients to satisfy crop demand temporarily until a soil application can be made.

Factors that may improve the effectiveness of foliar nutrient. Application during early morning or evening hours. Application when temps. Are less than 85 0 F. Relative humidity greater than 70% Inclusion of a high quality adjuvant. (increases its effectiveness)

Cont. Wind speed less than 5 miles per hour Application to young, actively growing tissue as compared to older, harden-off tissue. Application to expanding buds in perennial woody crops.

Calibration of Application Equipment. Look at tables 7-3, 7-4, & 7-5.