Smaller Sips Beat Big Gulps: Cyclic Irrigation for Nursery Crops

A very common and standard practice for outdoor nursery producers is to irrigate their containers one really large volume of water a day. But we see several problems with this. A common alternative to this single irrigation application is we suggest to growers that they can irrigate their crops in a cyclical fashion. And what that means is you take that total volume of water that you apply as you would in a single irrigation, but you split it up into separate increments. that first irrigation in the morning to fill those substrate pores with water. That afternoon irrigation will replace water that was lost through transpiration in the morning, and then that third final irrigation cools down the plant during the hottest part of the day. We've been studying cyclical irrigation and outdoor nursery production for 20-30 years, but we've seen a lot of benefits when you compare it to a single irrigation application. Some of the benefits are improved plant growth and development with the shoot and the roots, We suggest to growers that they should irrigate their crops cyclically throughout the whole production season, but we recognize that this might not always be feasible. The objective of this research is how long a grower needs to cyclically irrigate to still receive a lot of those same benefits as you would throughout the whole production season. We irrigate cyclically for 30 days, 60 days, 90 days, and 120 days. We are measuring substrate fertility. Growth index, we measure the height, the width. We measure chlorophyll count, so how green those leaves are. And we also track stomatal conductance, how well the leaves can conduct water through the tissues. We are putting a lot of efforts and energy into measuring the root system. Roots are the unseen engines of the plant. They are responsible for all the water and nutrients that the plants are really taking up. So what we are really trying to understand is can we use irrigation management practices to stimulate, strengthen, hasten root development in our container plants. We are still in the middle of conducting this experiment, but that might increase some of that flexibility and hopefully more growers can adopt this management practice.