Monday, May 27, 2013

A wet Spring

Ajay Nair
Department of Horticulture
Iowa State University

This past week I time traveled to my nursery days and the song which I wanted to sing badly was "Rain rain go away...Come again another day, Little Johnny wants to play". Things have been fairly wet this spring. The ground is saturated and it is hard to get in the field and plant. We need the rain but it is the timing that is causing  issues. It rains and the ground starts to dry in 3-4 days but then it rains again. As compared to last year we are late in our plantings. Last Tuesday we flail mowed our cover crops (cereal rye) and gave a shallow till to dry the soil faster. We waited for three days and last Friday when we got a small window, we went full throttle and banded fertilizer and laid plastic. Banding fertilizer in the area where the plastic is laid has several advantages:
1. Less fertilizer is used
2. Fertilizer not available to weeds that grow in the alley-way between raised beds
3. Promotes sustainability by reducing fertilizer usage

Above: Cover crops being flail mowed
Below: Plastic mulch layer in action
It is unfortunate that the rain is disrupting and delaying planting, but vegetable growers should take utmost care before deciding to run any machinery in their fields. One of the concerns is soil compaction. Under wet conditions, the effect of soil compaction could go as deep as 2 feet, depending upon the axle load of the tractor.  Heavily compacted soils contain few large pores and have reduced rate of water infiltration and drainage in the compacted layers. This can can increase runoff, thus increasing soil and water losses. Compaction directly limits root growth of crops and has the potential to reduce crop growth and yield. This year it might a little tight to find the perfect soil moisture or field condition to lay plastic mulches, all we can do is be prepared and ready to get in to the field as soon as there is an appropriate rain-less window. Meanwhile, on a lighter note, I will continue with my nursery rhyme.....Rain Rain go away....come again another day......
Normal and compacted soil

Monday, May 20, 2013

Planting time musing

Ajay Nair
Department of Horticulture
Iowa State University

Weather is fascinating. It surprises you in many ways. After months of conversation about not having moisture in the ground and a slow recovery from drought, here we are, talking about too much water in the ground! The level of anxiety among fruit and vegetable producers is on the rise. We at the Horticulture Research Station are on the same page. Every time one waits for a sweet 2-3 window to till the soil and roll the plastic mulch layer, a thunderstorm rolls in with 1-2 inches of water!

Things are a little different at the eastern end of the state, thanks to the well-drained sandy soils. It rains but you can be in the field the next day. But they have their own woes with lower organic matter and water holding capacity soils. At the Muscatine Island Research Station, Fruitland, IA  our sweet corn is 2-3 inches tall and the potatoes have sprouted and getting ready to come up the soil. We installed lysimeters in our potato sweet corn biochar study on 05-08-2013 to collect water leaching out of those soils. It will be an interesting finding to know how much of nitrates are being tied up by the biochar. A large number of high tunnel growers would be happy that this intermittent rainfall is not creating problems with their planting schedules. Most high tunnel growers have planted their crop and are looking forward to a good growing year. Our tomato plastic mulch study at the Armstrong Research Station, Atlantic, IA got planted 05-10-2013.
    Sweet corn at Muscatine
Lysimeter installed
Plastic mulch study at Armstrong Research  Station
Our lab was all excited for today (05-20-2013) to start laying our plastic mulch but the rain last night played a spoilsport. Oh well, there are things to get done in the lab. So here we are, waiting 2-3 days for that perfect level of soil moisture where the plastic mulch is laid down to perfection (straight, tight, and with good soil contact).