Growing Almonds with less Nitrogen

With sky high nitrogen prices and rock bottom almond prices growers are facing a challenging season this year and are under pressure to maintain yields with lower inputs. Better understanding how the timing and form of Nitrogen dictates growth in almonds can help improve grower returns.

Nitrogen inputs in almonds are inefficient

Nitrogen use efficiency on almond crops ranges between 50 and 75%, so there is potential to reduce inputs whilst still getting more N into the crop.

Standard recommendations for N rates vary for almond production depending on predicted yield and age of the trees. When calculating the amount needed NUE (Nitrogen use efficiency) must be factored in to allow for the nitrogen that the plant does not receive.

Typically, farmers are needing to apply half to a third more than the crop needs due to the amount that is lost to the environment.

Why do we lose N in almond orchards?

Nitrogen is not stable in the environment, when we apply manures and fertilisers to trees either broadcast or through fertigation what we put in the ground is not the same as what gets taken up by the crop.

Microorganisms in the soil compete with plants for applied nitrogen, and rapidly alter the form applied. Through a series of processes ureic nitrogen changes to ammonium, and ammonium changes to nitrate. Along the way there are losses to the atmosphere (due to ammonia volatilisation and NOX) and to groundwater from leaching (as nitrates and urea).

Plants do not receive all the N that is applied, and what they do get is taken up mainly in nitrate form, regardless of what form was applied.

Lono is a unique nitrogen fertiliser that uses LimiN chemistry (developed in the UK by Levity Crop Science) to supply stabilised amine N (SAN), that is taken up by the crop in the amine form and not lost via volatilisation and leaching. This technology enables farmers to lower conventional nitrogen applications on almond crops without reducing the nitrogen available to the trees.

What difference does form of N make?

Because there is such a disconnect between the quantity and form of what is applied and what the trees actually take up we must be careful in how we interpret data from studies comparing different fertilisers in almonds.

Recent studies of conventional fertilisers applied to almonds in California show no significant difference in yield between different sources of ‘big bag nitrogen’ applied as UAN32 and CAN17 despite the having quite different mixes of nitrogen types. This is not surprising when we consider that for all conventional fertilisers a lot of the N is lost, and is mostly taken up as nitrate. What is applied is different, but what the plant receives is similar – in essence the crop is receiving broadly the same thing, hence we see similar results.

It is tempting to conclude that for almond growers the form of nitrogen is irrelevant, but they all have very different roles in plant metabolism and can understanding of this can be used to improve yields.

Nitrates (NO3), the dominant form that almond crops receive are processed in foliage. The almond tree then transports them to leaves, where they are converted into amino acids and used for growth. As nitrates accumulate in foliage pending processing, almond trees start to increase production of growth hormones called auxins. This encourages vegetative growth.

Amines (NH2) are processed in roots using a shorter chemical process, they encourage production of a different growth hormones called cytokines that encourage root growth and reproductive (flower and fruit) development.

Different types on N encourage different types of growth – we don’t see this when we apply conventional N, as the plant receives what is applied mostly as nitrate. But by applying different forms of N is stable forms, we can influence where a plant grows through a process known as ‘growth partitioning’.

Lono supplies stabilised amine N (SAN). Research shows that Lono influences where crops allocate growth – encouraging investment in root and reproductive growth over vegetative growth.

Small applications of Lono can be used to influence where almond trees grow, directing resource towards root development, flower development and kernel filling rather than towards vegetative growth. When crops build the right parts of plant, smaller applications can have a disproportionate impact on yield.

When is the best time to apply to almonds?

Timing of nutrient supply in all crops is very important for getting the best from inputs. Nitrogen uptake in almond trees is highest between bloom and the end of kernel fill.

Before bloom almonds rely on mobilising reserves already contained in the woody tissues, and soil applications have little effect. After kernel fill and before leaf fall uptake is also limited. The best way to influence yield during this period is to apply a dormant spray to the wood (see our article on why dormant sprays lift almond yield).

The best way to use Lono to influence yield is to make applications through the time of peak nitrogen demand by the crop using a program of 2-4 applications of 5L/Ha between onset of bloom and the end of kernel fill.

In most permanent tree crops every 1L/Ha of Lono added to a program allows a reduction of 3kg/Ha of conventional nitrogen from a programme. A program of 5L/Ha applications could remove 60Kg/Ha of conventional nitrogen fertiliser whilst improving the crop. Alternatively Lono can be applied additional to a conventional programme to improve yields.

What are the advantages of using a Lono programme on Almonds?

One benefit of running a more efficient nitrogen program is the reduction in applied N lost to the environment. This ensures every penny spent goes into the crop rather than as groundwater or air pollution.

There are also major agronomic benefits to this approach. Conventional nitrogen applications over-emphasise nitrate effects, giving a greater emphasis on vegetative growth and a lesser emphasis on root growth, fruit development and buds. This over time weakens trees and leads to there being a biennial yield cycle (big yield small yield).

Lono applications encourage almond trees to allocate growth more evenly, reducing the dominance of vegetative growth and improving root, fruit and bud development. This helps improve grading, homogeneity and yield for the current crop, whilst also lifting yield potential for the following season.

Finally, the improved root development in Lono treated trees helps them cope with stressful growing conditions, low rainfall and high and low temperatures. This reduces shedding of fruit during periods of stress.

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Please contact us for more information about purchasing Lono.

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Award winning scientist and experienced agronomist. With multiple patents, and proven track record of product development in biostimulants, pesticides and fertilisers.

Author: David Marks

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