Climate adaptive demonstrations

Cutting off irrigation as melons mature can help to advanced ripening, decrease splitting, and allow for a higher concentration of sugars. Determining the date to do this was tricky with 5 different varieties. After consulting with Lucas Nebert of OSU’s Dry Farming Program, we decided to have our last irrigation on August 8.

Providing water to melons during their most critical growth stages and decreasing water in the less critical stages can help farmers be more precise with irrigation. When we finish entering and summarizing the data for this project we’ll share the findings. Above are our total irrigation numbers (see images).

Other important numbers that we collected during the growing season were harvest and weeding cost data points. Above are graphs detailing this data.

After the field day, when the melons were done producing, we learned a valuable lesson. Those moisture sensors are difficult to get out of the field! We take this issue seriously, as we don’t want farmers to have to waste valuable time and money extracting the sensors from the field. The 36” sensors were especially a pain.

We attempted to dig out the moisture sensors in mid-September, using water to soften the soil when it got too compacted. Unfortunately, it took us several hours, and we broke 7 out of 30 sensors. This is a 23% rate of breaking sensors, so we do not recommend attempting to dig them out with a shovel.

After some research, we have found that a leveraging method appears to be the most successful. In Corvallis they were able to pull the sensors out with rope and a T-post puller. Here is a message from Lucas Nebert:

“We have been using a t-post puller with a rope lately, and have been able to tie the rope to the PVC in such a way to get enough grip so it doesn't slip up the PVC when you pull. I'm far from a knot-tying expert, so if I can do it, I think others could. In a pinch, I also have just used a single t-post as a lever (also with a rope) to pull it up and out of the ground.”

We found this tool online, which is marketed as the official tool to get the sensors out of the ground easily. We’re going to invest in one of these and try it out.

The trial results will be shared in the winter along with results from similar trials in Corvallis and Central Point. Stay tuned for more!

Using NWREC’s Deficit Irrigation Melon plot at the Learning Farm, we have tracked melons grown with dry farming practices and deficit irrigation for two seasons. We track melon growth using the growth stage guide from the Croptime project. See how the melons progressed above.

We are starting to notice some difference in plant sprawl. In these pictures, look at the foliage cover: there is more soil and stem visible in the photo of the dry farmed Lilly melon plant than the 30% deficit irrigated plant.

Last year's dry farm melons had a first flush of flowers that matured into melons, but did not develop a fully mature second crop. As this season progresses, we will see if there are similar results, and how the deficit irrigation plants

• From Transplant through week 6: Similar plant progression in all treatments
• Transplanted with 3 to 4 leaves
• By week 3 after transplant, the plants in all four treatments had between 5 and 6 fully unfolded leaves on the main stem.
• By week 4, all plants had 3 or 4 secondary shoots and had grown between 1 and 4 elongated female buds.
• By week 6, each plant had between 5 and 8 female flowers open. Small fruits are beginning to form.
• Week 7 – An abundance of flowers

This week we are starting to see some divergence among the growth rate of the treatments. The Dry Farm treatment has the fewest female flowers per plant, with around 10. The 30% deficit irrigation has the most flowers, around 20 per plant. It is interesting to note that the amount of water each treatment has received does not correlate to the average number of female flowers for each plant.

This year at the Learning Farm, we’re growing melons! The melons were transplanted on June 7, 2024, and thankfully, there was some rain not long after planting. We’re combining what we learned last year from the dry farming and irrigation scheduling plots and putting it all into one demonstration area. This year, we have dry farmed melons, two deficit irrigation demos; and one demo where we are irrigating about an inch of water per week. We are growing five melon varieties, and all of these are in each of the demonstration plots. Once the fruit is ready to harvest, we’ll be looking at maturity dates, yield, fruit quality, and sugar levels.

The moisture sensors are installed within the plant rows, and the drip irrigation is about 6 inches from the plants. We’ve been noticing that the water is not reaching the moisture sensors in the deficit irrigation plots. Our first irrigation was on July 10 in the 30% depletion plot, and we didn’t see as much of an increase in soil moisture as we expected after one inch of water was applied to these plots. We’re looking more into this and are taking notes for next time, perhaps putting two drip lines down on either side of the plant for more even distribution.

We’ve been working with Lucas Nebert and the OSU’s dry farming project to determine deficit irrigation rates; we are using 30% and 50% of available soil water depletion. When these levels are reached, we irrigate these plots. Soil moisture sensors were installed at 6”, 12”, 24”, and 36” depth in Lilly, one of the melon varieties, in each of the irrigation demonstration plots. These sensors were installed ten days after planting. The readings from the moisture sensors inform when to irrigate the deficit irrigation plots.

Soil Moisture Sensor readings at 6”, 12”, 24”, 36” in each treatment. Blue drops denote irrigation applications (in inches), and clouds represent precipitation events (measured in inches).

Piper Westhead, an OSU horticulture undergraduate student working on this project, has been taking soil moisture readings this season and created the graphs above to illustrate water use and irrigation of the demonstration plots. In these graphs, as the numbers go up, it denotes a decrease in soil moisture.

We used penetrometers to replicate the force needed for a root to move down through the soil. On August 3, we measured surface (6”) and subsurface (18”) hardness in the sweet corn by slowly pushing the penetrometer through the soil of each treatment. The sweet corn was being irrigated at the time of sampling. We recorded three readings of each bed for six total samples per treatment. The penetrometer scale runs from 0 to 300+ psi, readings exceeding 300 psi indicate root growth inhibition and the presence of hard pans.

We observed distinct differences in weed levels among the tillage treatments. To accurately quantify these differences, we recorded the time it took to weed each treatment. Victoria and Heidi conducted the hand-weeding for each treatment collaboratively. The sweet corn is planted in 40-foot beds, with two rows per bed and two beds per treatment.

There were hardly any weeds in the no-till plots, while the conventionally tilled plots had a robust population of grass. It took just over twice as long to weed the conventionally tilled plots compared to the reduced tillage plots and eight times longer than the no-till plots.

Surface level compaction had the greatest resistance in the no-till plots and the least resistance in the reduced till plots. Subsurface compaction levels were similar across all three treatments, ranging from high to very high. The presence of hardpans varied from depths of 3” to 15” to none throughout the treatments. We were unable to break through the shallow (3-6”) hardpan in one of the no-till beds. These beds were tarped this spring, and a farmer we interviewed mentioned that rain hitting the tarps could increase soil compaction. This may explain what we are observing. Additionally, we encountered compaction from the wheels of the compost spreader, which did not align with the wheel tracks of our beds. (Figure 3)

We applied 3 inches of compost to the tops of each bed. The compost was worked in differently depending on the demonstration.

Dry Farm plots with a perfecta.

Conventional Tillage and Irrigation with a rototiller.

Reduced Tillage with a harrow.

No-Till we raked it smooth and left it directly on top of the bed

Last week Lucas Nebert (OSU Dryfarmed Corn Project) came out to NWREC and used his bucket auger to collect sub soil and determine site suitability for the dry farming demonstration.

The soil was well drained all the way down and was free from significant compaction layers. No grey (anoxic) layers were observed in this sample.

Lucas collected soil from the 24-36 in layer for nutrient and pH analysis.

We plan on replicating some of Lucas's squash trials this year and will be growing Delicata (Zeppelin) and Georgia Candy Roaster.