Digging Deeper: About water, young nuts and beetle banks
In the series 'Digging Deeper' you can follow the developments and results of Inagro's own agroforestry plot from the front row. In this edition you can read more about the impact of the wet spring on the plot, the (re)planting of walnut trees on beetle banks and, as usual, we again give an overview of the activities on the plot since the last update.
Corn is delayed
It's been a while since you got an update from on our agroforestry plot. Not without reason. In the previous edition of Digging Deeper you could already read that the harvest of leeks was delayed due to the rain. In the end, the farmer could only harvest in the first week of February. The quality of the leeks was good, but the harvester clearly left its mark in the wet soil.
Since then it remained remarkably quiet on our plot. The persistent rain and water-saturated soil still does not allow any field work. This year we are growing corn between the walnut trees. Although it should have been sown several weeks ago, there is still no trace of corn. The pair of partridges and the other birds in and around the field are having a great time because of this.
Trees are growing and blooming
The corn cultivation is delayed, but the nut trees (and hedges) are not letting up. Of course, they are still small saplings, but despite the wet conditions, they generally seem to be thriving. You can read later on that this is not the case everywhere on the plot, however.
The first leaf buds sprouted around April 9th and by May 16th, all nut trees were in full leaf. At the same time, many of the trees were producing male catkins for the first time since planting. One moment of late spring frost during the night of April 22nd-23rd (-1°C) threatened to spoil the situation, but in the end neither the leaves nor the male catkins suffered much damage. The female flowers, which develop at Broadview after the catkins, also emerged in late April.
To ensure that the saplings invest primarily in their vegetative growth, we will remove (squeeze out) the saplings wherever possible.
With walnut trees that sprout and flower before May 15th, such as Juglans regia 'Broadview', there is always a risk of frost damage and consequently substantial loss of production. Most current varieties grow and flower before May 15th, but research on late-sprouting walnuts (LUW trees) is ongoing and could provide a solution here in the future. For now, these late-sprouting varieties are not yet commercially available.
Partial replant...
The past wet year also exposed a weak point in the plot. The eastern side of the plot in particular was a lot wetter, and the trees here had their feet in water for long periods of time. Two of the five rows of trees are in this wet zone (the two longest rows at the bottom of the drone picture above). Because of the wet conditions at planting time, the trees in these rows ultimately did not take root and replanting is needed.
When digging out the dead trees, it was clearly visible how the wet conditions had caused the roots to all but completely die and rot. In total, we need to replant 22 trees as a result. A cost that will have its impact on the economic reckoning at this early planting stage.
...on beetle banks
But before we replant the trees, we are performing an additional structural intervention to avoid similar problems in the future.
- We will first slightly raise the two rows of trees in the wet zone of the plot with newly supplied earth according to the principle of a beetle bank. This embankment ensures first of all that the trees are drier, but also provides a wintering habitat for beneficial insects such as ground beetles.
- We seed the embankment with a perennial, low-maintenance mixture of pollen-forming grasses and a small portion of annual and perennial herbs.
At Inagro, we already have a beetle bank (without trees) on which we were able to gain some practical experience in previous years ( picture on the left). So on the agroforestry plot these will look similar, but with walnuts on top.
But first: a permit!
Specifically, we will construct two beetle banks, each 3 m wide and 40 cm high. One about 80 m long, the other a little more than 100 m. With these dimensions, an environmental permit is required for the construction (> 30 m³ of earthmoving at plot level). Moreover, because these embankments are located in flood prone areas (see picture on the left, embankment location indicated in yellow and trees as red spheres), the raised volume must also be compensated (read: excavated) elsewhere.
The permit application is currently being prepared, including a plan with the location of the embankments and proposed compensation zones. The entire application process and final construction will quickly take several months. So we will only be able to plant the new trees next winter.
IN THE PICTURE: The plot and activities since the last edition of 'Digging Deeper'
