Horticulture solutions
Horticulture is a key part of the New Zealand economy. Plant & Food Research reports that produce from the horticultural sector was worth more than $9 billion in 2018. This includes about $5.5 billion in export earnings. The country’s biggest horticultural exports are kiwifruit, wine and apples followed by potatoes, avocados and onions. Exports also include things like fruit juices, vegetable seeds and flowers.
Sustainable horticulture
Bryan Hart is Senior Crop Manager for AS Wilcox & Sons. Bryan explains the techniques his company uses to stop soil erosion and make the most efficient use of irrigated water.
Question for discussion:
How do contour oat strips in the potato fields work like riparian strips next to streams and rivers?
New Zealand has an estimated 135,000 ha of cultivated horticultural crops. The horticulture industry adapts to consumer and market needs. For example, in 2010, there were fewer than 5,000 ha of vineyards – 10 years later, vineyards covered 35,000 ha.
Environmental impacts
Horticulture involves preparing the land, adding water and nutrients when necessary, providing protection from insects and diseases and harvesting the product. Each of these actions has the potential to impact water quality:
Repeated cultivation and harvesting can compact soil. This increases the likelihood of surface run-off, especially during heavy rainfall. Run-off water can carry sediment, nutrients, herbicides and pesticides to surrounding streams and rivers.
Some cropping systems rely on irrigation – water taken from groundwater or surface water. The amount of irrigated water needs to match crop needs so that nutrients and pesticides do not leach into groundwater or run-off. Taking too much water can impact stream habitats.
Pest control can impact water quality from spray drift or if pesticides run off into waterways.
Reducing chemical leaching and run-off
AS Wilcox & Sons use a variety of techniques to minimise pesticide and fertiliser use when growing potatoes. Senior Crop Manager Bryan Hart explains some of them.
Jargon alert: Bryan talks about New Zealand GAP. GAP is an acronym for good agricultural practice. NZGAP certification provides assurance that fruit and vegetables grown in New Zealand are safe and sustainably produced.
Question for discussion:
Why do you think European supermarket chains would be interested in water quality tests done in New Zealand?
High-value exports
There are a number of industry and government agencies that oversee sustainability practices in the horticulture sector. Regional councils issue resource consents regarding the amount of water growers are allowed to take. Councils also offer advice on sediment control and nutrient management.
New Zealand is a niche exporter of high-value foods to markets that rank among the world’s most discerning in their sensitivity to issues of quality and sustainability.
Plant & Food Research
Horticulture New Zealand established NZGAP (New Zealand Good Agricultural Practice) more than 20 years ago. It is a quality assurance programme that provides an accountable, traceable system from crop to customer. NZGAP’s scope includes food safety, social practice and the environment. Growers gain NZGAP certification after inspection by an auditing team. This type of certification is important for local and export markets.
Soil type and nutrient availability
Many soils in the northern part of the Waikato region are ideal for growing vegetable crops. Bryan Hart, Senior Crop Manager for AS Wilcox & Sons, explains why Patumahoe clay loam is good for cropping and why growers need to know about soil chemistry.
Question for discussion:
What does Bryan mean when he says that fertiliser can be locked up by the soil?
A S Wilcox & Sons Ltd – vegetable growers
A S Wilcox & Sons has been growing potatoes, onion and carrots for more than 50 years. As a family business, Wilcox believes in investing in the health of the soil and the environment so it can continue to operate for generations to come. The company is NZGAP certified – its products are sold in New Zealand and exported to Europe and Asia.
Wilcox uses a number of methods to reduce surface run-off and erosion. The first action takes place right after planting. Heavy vehicles can compact soils when crops are planted. The wheel tracks can act like drainage channels and allow water to flow like miniature streams. Wheel tracks are ‘ripped’ – making shallow cuts just below the cultivation zone – allowing water to infiltrate the soil.
On sloped soils, Wilcox plants oats in contour strips every 30–50 m. Water and sediment that does run off is stopped by this natural barrier, and the oats capture the nutrients for their own growth needs.
Wilcox uses integrated pest management. They border the crops with plants that host natural predators. When pesticides are needed, the company selects chemicals that target the particular pest, keeping the natural predators and other insects out of harm’s way.
Acknowledgement
This article has been developed in partnership with the Waikato Regional Council as part of the Rivers and Us resource.
Waikato Regional Council
Waikato Regional Council is a local government body. They work with communities, iwi and industry to sustainably manage natural resources, enabling a strong economy and a high quality of life for all. Their activities help look after the region's water, soil, air, geothermal areas and coasts.
