Being Responsible for a Sustainable Water Supply

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Agricultural activity in Nova Scotia has benefited from a relative abundance of freshwater available from rivers, storage ponds and groundwater sources. Annual precipitation consistently exceeds 1,000 mm/year, providing reliable recharge to aquifers and associated baseflow to rivers. The unrelenting rain this spring probably hasn’t brought water needs to the forefront of people’s minds, yet variable weather patterns and increasing demands by farms, municipal utilities and industry will place increasing pressure on surface and groundwater supplies in the future.

 

Water withdrawals

Responsible water use is an important consideration for the agricultural industry in Nova Scotia. The horticulture and vegetable industry rely on various water sources for irrigation purposes. Nova Scotia Environment (NSE) requires that farmers obtain approval to withdraw water volumes greater than 23,000 L/day from a single water source. As an example, an inch of water applied to an acre of land using an overhead system amounts to 102,789 L (22,610 gal) of water; over 4 times the daily withdrawal limit. Currently, there are no fees for agricultural approvals; however, in some cases, a qualified professional may be needed to complete a withdrawal approval application. NSE has prepared guides for both ground water and surface water supplies (see links in Related Resources below).

 

A withdrawal approval is needed for regulatory compliance in order for NSE to properly manage water use in the province to ensure a sustainable water supply for all Nova Scotians. As part of this management process, an approval gives the approval holder the “first rights” to that water source. If you are an approved user, your water needs take priority over new interests in a given area. If you are a large volume user, but do not have an approval, your use is not properly documented and would not be included as a part of any future watershed assessments. As new withdrawal approvals are granted, if there is ever a shortage of water, i.e. due to a dry summer, you would have no recourse and your needs would not be a priority as compared to users with existing withdrawal approvals.

 

Water monitoring

A water flow meter is an effective means to document water use and track changes to water management practices. Flow meters are recommended for withdrawal approvals, although pump specifications and logging hours of use can be used as an alternative in some circumstances. There are a variety of flow meters available in the marketplace, although it is important to ensure it is properly suited for the situation, e.g. vertical, horizontal or oblique installation and compatible with water quality, e.g. impurities in water.

 

Irrigation management

Proper irrigation management ensures that the irrigation system is operated to match the crop, soil and climate conditions present. Irrigation should be scheduled to replace moisture losses in a manner that does not exceed the crop’s ability to utilize the water, or the soil’s capacity to store the water applied. Appropriate irrigation equipment selection and design, as well as good management and scheduling, will conserve water supplies while supporting crop growth.

 

A farmer’s observations and experience are often relied upon during the growing season; however, soil moisture sensors can help improve irrigation management. Depending on the crop, even mild plant stress can impact yield. Soil moisture sensors are useful tools to help irrigators to understand what is happening in the root zone of a crop. There are two basic groups of sensors for soil moisture monitoring:

 

  1. Water Potential Sensors: such as tensiometers and granular matrix sensors, (e.g. gypsum block and watermark sensors). These sensors measure how hard it is to remove water from the soil. This information coupled with an understanding of your soil texture (e.g. sandy, loamy, silty etc.) can be used to determine the amount of water in the soil that is available to plants.
  2. Soil Moisture Sensors: that give a percentage or relative content of soil moisture. These sensors measure the water content of a soil using the time or frequency of a pulse travelling between or returning to electrodes. The most common types are capacitance and time or frequency domain. Most sensors are accurate within 2–3% of the actual soil moisture.

 

The wide variety of tools and sensors available for assessing soil moisture can accommodate a range of farm needs regardless of farm size. With advances in technology, farmers can now access real-time soil tension sensor data with a mobile platform that allow growers to anticipate the water needs of the crop and schedule irrigation accordingly, e.g. https://hortau.com.

 

Water is a critical input into all farming operations. Unlike many regions of the world, we are fortunate to live and farm in an area where we have an abundance of high-quality water. The summer of 2016 was an example that highlighted that we are not immune from water scarcity in the province. Moving into an unpredictable future, it is in our best interest to understand the limits of the water resources we have and to manage those resources responsibly.

 

Resources:

Trevor Davison, Environmental Farm Plan Coordinator

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