AgConsult specialises in soil fertility and plant nutrition, especially for viticulture. In operation since 1988, we have provided independent fertiliser advice to farmers and growers throughout New Zealand. AgConsult Ltd works with a number of companies and individual advisers in the field where we provide comprehensive reports for growers, with fertiliser recommendations based on soil/petiole/leaf test results. A large percentage of our work relates to viticulture.

> tests offered


In the last six years we have expanded into Research and Development and General Consulting, with particular attention to issues like soil use sustainability and effects on soil biological activity and soil organic matter.
AgConsult Ltd has been closely involved with the development and field testing of a number of different products on the market today. We have been contracted to do field trials with a large number of different products on grapevines, pasture, kiwifruit, pip fruit etc. Specific areas of research included general nutrient availability, effect of type of application, vine disease resistance, calcium uptake in apples, general crop quality etc.

> research & development

Pasture Application Trial


We have organised training sessions and courses relating to soils, soil fertility and soil biological activity for a number of our clients. Our senior consultant Gerard Besamusca has been involved in numerous seminars relating to soils and viticulture/horticulture and is regularly invited to give presentations on relevant subjects. He is a member of the NZIAS (New Zealand Institute of Agricultural Science), NZSHS (New Zealand Society for Horticultural Science), ISHS (International Society for Horticultural Science), and is CPAg accredited.


Vine Establishment Trial

Most of our clients are involved with grapegrowing. There is a growing awareness of the importance between soil characteristics, soil management and nutrition on the one hand, and (grape and wine) quality parameters on the other hand.

Soil and vine management can greatly affect yield and quality. Understanding the processes involved means there is a potential for managing a number of important quality parameters in the wine making process. Examples are Potassium and must pH, Acidity, Ammonium and YAN nitrogen (stuck fermentations), colour and bouquet, sugars and tannins.

To manage these parameters effectively, monitoring soil and petiole/blade nutrient levels is essential. Obviously close communication with the wine makers is also required (juice/must analysis). Some varieties can have significantly different desired or medium petiole and blade nutrient levels. Rootstocks affect the rate at which elements like potassium, magnesium, calcium and nitrogen are taken up by the vine.

Many grapegrowers routinely take soil and petiole samples. Any responses to the findings of these tests are usually only aimed at maintaining vine physiological minimum nutrient levels with little eye for the crop in terms of yield or desired quality parameters.

It is this void that we are trying to fill with our consultancy. By using more comprehensive soils tests, regular petiole and blade testing, the aim is to promote healthy vines which grow the desired quality grape. This means taking into account the effects of canopy management, covercrops and climate.

Databases can be built up using all this information to compare effects of different treatments on wine quality for each vineyard or vineyard block.



One special area of interest is the role soil biological activity plays in maintaining vine health and crop quality. Soil microorganisms, including beneficial mycorrhizal fungi, play a major role in nutrient uptake of the vine. These organisms also help protect the vine against nematode attack and other pathogens.

Optimum soil biological activity for a paddock producing pasture is quite different from the optimum soil biological environment required for grapegrowing. In the latter case we need more fungal biomass including mycorrhizal fungi to create a typical vine environment in the soil. Promoting mycorrhizal fungi will dramatically increase the total soil volume the vine will have access to source water and nutrients, and will benefit uptake of elements like phosphorus, zinc and calcium.

Promoting or maintaining optimum levels of soil biological activity for grape growing is one of the goals of vineyard soil management. It will not only enhance vine nutrition and vine health, it will also help maintain soil health long-term, and in the case of newly planted vines help their establishment.




Grapevines have natural abilities to resist pathogen attack. This ability varies between varieties, and also depends on environmental factors.

Understanding more about how the vine’s own “immune” system works, help us produce stronger and more resistant vines. Although it may not always be possible to completely discard fungicide use, it certainly seems possible to reduce the need for fungicides and/or increase the efficiency of fungicide use.

One of the ways we can do this is by using (natural) elicitors that can “prime” the vines immune system so it is better prepared against pathogen attack. By eliciting the vine’s immune response, a number of defence compounds are produced within the vine (and grapes). One of the more important such compounds is Resveratrol. Resveratrol is a plant defence chemical (phytoalexin) that is involved in imparting a level of disease resistance to the plant.

Helping to increase the vine’s resistance to pathogen attack can also be done by promoting beneficial microorganisms on the leaf surface.

A healthy leaf contains many different microorganisms on the leaf surface. Under normal conditions they will help resist pathogen invasion by competition (food and space) as well as the production of specific antimicrobial substances that help keep pathogens at bay. Unfortunately, in many vineyards management has reduced the presence of a diverse and beneficial population of microorganisms.



Too often, soil and fertiliser management is only reactive and not integrated. If soil samples show deficiencies some fertiliser will be applied. If petiole samples show deficiencies a foliar spray may be applied. However, typically here is no coherent nutrient, soil and vine management system in place. Information from soil samples and petioles is not used to its full potential and is not properly retained for easy future access.