AGRICULTURAL ENGINEERING SPECIALISTS REPTEC

Making good effluent irrigation decisions.

effluent irrigation

On farm benefits to effluent irrigation of course include fertiliser savings, improved soil condition, and compliance with council rules or resource consent. But always avoid fines by making sure your effluent system is operating within the law and running efficiently. Buying the right equipment and regular maintenance are also key to water conservation along with correct application rates. Key to your decision making for application rates is understanding the soil water deficit in order to prevent ponding and run-off and to avoid applying effluent to saturated soils.
Dairy Nz also provide some great informational booklets on good decision around effluent irrigation.

Choosing and maintaining adequate equipment for effluent irrigation.

At the heart of any dairy farms effluent system the pump is subjected to the harshest of conditions. The type of pump and duty should be chosen depending on the application for which it is intended whether it be greenwater or un separated effluent. Pump efficiency is at the source of the decision making process along with reliability. Effluent pumps need to be sized and suited correctly to ensure they perform at their best and to minimise downtime due to blockages or breakdowns.

Types of pumps include:

Vertical effluent pumps
Generally multi-stage pumps capable of passing fibre as well as small solids, ideal for greenwater for a high head and/or long distance to irrigation, also for travelling rain guns.
Effluent surface pumps
These pumps are used only when I very high standard of greenwater effluent is being pumped. These pumps provide efficient, easy maintenance pumping with good pressure. Perfect for injection into existing irrigation systems or running systems on effluent alone. They are very versatile with many different sizes and duties to suit any application.
PTO pump
One of the most cost effective and efficient ways to pump effluent (and water – irrigation) on your farm. It utilises an existing resource – your tractor – so it’s important to select a PTO pump matched to the HP/kWs of your tractor. It’s also important to ensure you select the right PTO pump for the head loss of your effluent system, the volume per hour to be pumped and the contour of your farm.

Types of Irrigators include:

K-line & Pod irrigation
Suitable for odd-shaped or small areas and slopes where pivots are not feasible. These irrigation systems are low-cost entry-level products which do require a high labour input. Low application rates reduce ponding and allow better retention of nutrients. Application can be controlled with automated timers.
Pivot Irrigation
This is a highly-efficient broad acre irrigation method suitable for 10ha or more. Pivots require very little labour input, operate on low pressure, have a long life and low running cost. Effluent injection and Under Slung options are available.
Linear Irrigation
Another very efficient broad acre irrigation option, best suited to rectangular blocks of 10ha or more, ideal for areas of cropping. Delivers a highly-uniform, low application rate but a high degree of filtration is required. An underslung effluent system with specific effluent nozzles can be installed which can handle a greater solids loading. This equipment has a long life, operates on low pressure and delivers low running costs. They minimise water loss and achieve optimum crop growth. You can control the precise application amount (right down to fine droplets for sensitive crops) and can turn sections of sprinklers off to keep stock yards, buildings, tracks or silage dry. These machines will operate 24/7 and require minimal labour input.
Travelling irrigators
These systems require higher pressure and more labour input than pivots, and can cost more to run. But the benefit is they fit odd-shaped areas and allow trees and existing infrastructure to remain in place. They can be used for both irrigation and effluent application.
Fixed & Solid Set sprinklers
When used on the outside of pivots or linear irrigation systems, these sprinklers are a highly efficient and flexible way to use water. They can be used for specialised areas and are ideal for hillsides, which cannot be pivot irrigated. They also require less labour than pods for odd-shaped areas. These systems can involve higher maintenance costs and can be prone to wind losses.

For maintenance and repair of irrigators contact Reptec for help.