Two thirds of the way through spring our micropaddocks are approaching full canopy. Onions that progressed so slowly over winter are growing rapidly and peas planted in September are well established. A key question now is when to irrigate.
ThinkWater installed flushing sub-mains in our drip irrigation block and that system is all primed. We expect to run the dripline every couple of days, applying 10mm of irrigation.
With wheels and a sprinkler package from WaterForce, our Drumpeel linear irrigator is finished, fully commissioned and tested and has completed its first lap of the MicroFarm.
Thanks to a radiometer from Steve Green and anemometer from Plant and Food Research we have a full set of climate readings on-site. HortPlus use the radiation and wind speed together with temperature and humidity to produce PET readings so we can track water use as well as rainfall. See details here>
We complement the climate data with soil moisture monitoring. Our weather station has an Aquaflex sensor which is tracking dryland pasture soil water content.
We need to adjust PET to our crops’ individual ET values. This means reducing potential pasture water use to a partial crop cover water use. The crop factor is a combination of crop type, ground cover and soil surface evaporation and prior to canopy closure most growers will be making best estimates. We have been working with a developer on a simple sensor to help assess groundcover. Figure 2 shows sensor images and percentage of ground cover (green) in two areas of peas.
So what is the actual soil moisture in the different paddocks? HydroServices installed neutron probe tubes into our crops and gives weekly status reports. The neutron probe data is collected as a number of depths through the profile, so it also helps determine active root depth. We just got to trigger point in before 18mm of rain fell. A week later we got another 8mm to top things up.
This spring we also tried Cosio® cover cloth on the onions and the peas. We were a bit late getting the covers and so didn’t get all the information or benefits we hoped for. We covered the onions at early two leaf stage and left them on for several weeks. In that time they caused some plant form disturbance and the more horizontal leaves did appear to get some chemical burn. Next time the covers will be on much earlier, possibly from planting, and off at two leaf stage.
We also covered the peas. This was in part due to frustration of pigeons consuming vast quantities of seed then later nipping the shoot tips of the survivors. More shotguns earlier next season! Although there was likely some seed loss before we got the covers on, we did see significantly more growth in the covered areas. When we first took the covers off, our ground cover sensor suggested as much as 50% more under the covers. The plants were notably taller and visibly covered more ground. Weeks later there is still a significant difference.
Once again though, the pea crops have high variability, both population count and plant size. When we harvest a whole crop in a matter of hours, being days apart in maturity is not acceptable.
The MicroFarm discussion group determined to put strong focus on preparation and planting next time. Peas can be a profitable crop, especially in combination with a second crop such as sweetcorn or beans. But if we don’t get even germination, even development and higher yields, it can be a great disappointment. We think growers should pay attention to this crop, aim to do well from it, and avoid temptations to do everything as cheaply as possible.