As water scarcity increases, scientists around the world are looking at growers’ options for irrigation methods.
Here are three studies with some interesting results.
How Negative Pressure Irrigation in Field Production Reduces Inputs
Researchers set out to discover how a fairly new irrigation method compares with current vegetable industry irrigation methods. Negative Pressure Irrigation (NPI), a subsurface irrigation technique, has had a lot of attention lately. It promises to reduce inputs, both water and fertigation.
A couple of the known advantages of NPI is that it supplies irrigation based on the crop’s consumption of soil water,
and it keeps soil water content stable during the crop’s growing period.
But how does it impact crop growth and yield?
An international team from China, Belgium, and the U.S. compared how cucumber (container grown) and field tomatoes fared with different types of irrigation.
The cucumber portion of the study resulted in higher yield. For most vegetable growers, however, it’s the results of the tomato study that will hold the most interest. The team compared NPI with furrow and drip irrigation.
They found NPI reduced fertilizer and irrigation inputs when compared to both furrow and drip irrigation. Although there was no significant increase in yield, neither was there
a decrease.
Authors: Shengping Li, Deshui Tan, Xueping Wu, Aurore Degré, Huaiyu Long, Shuxiang Zhang, Jinjing Lu, Lili Gao, Fengjun Zheng, Xiaotong Liu, and Guopeng Liang
How Salty Is Too Salty?
With water availability at risk, researchers are taking a closer look at what happens to crops with lower quality irrigation water and with a lowered amount of water.
Brackish water may have a negative impact on plant growth, but at what point does it become detrimental? And how far can growers push reducing irrigation levels before plants suffer?
Brazilian researchers studied how collards were impacted by five different levels of soil conductivity (salinity), each applied at four different levels of irrigation (55%, 70%, 85%, and 100%).
The plant scientists chose collards since it’s made up of 90% water and will display adverse irrigation impacts quickly.
The research team used several methods for evaluating the results: plant height, stem diameter, the number of leaves, biomass (dry and fresh), and green color index.
With so many parameters, the study has complex results. Overall, irrigation levels had a bigger impact on yield and quality than salinity. Brackish water may be an option if conductivity levels are not too high.
Authors: Jonathan dos S Viana, Luiz Fabiano Palaretti, Vinicius M. de Sousa, José de A. Barbosa, Antonio Michael P. Bertino, Rogério T. de Faria, and Alexandre B. Dalri
Mycorrhizae Allows for Lower Inputs
A Brazilian/Spanish research team carried out three experiments to determine if mycorrhizae in low irrigation and fertilizer situations impacts vegetable yield.
For each experiment, the team grew tomatoes in soil with no temperature controls in a greenhouse in Northern Spain.
The first study reduced fertilizer doses to tomato plants inoculated with mycorrhizae. Fruit number, total yield, and fruit quality increased.
The second tested irrigation levels with inoculated tomatoes — normal farm levels, 75% of those levels, and an optimized irrigation program based on weather and plant-growth data. Deficit and optimized irrigation increased yield and fruit size but not fruit-soluble solids concentration or color. There was no effect from mycorrhizae inoculation.
For the third experiment, the researchers reduced fertigation by regulating irrigation doses based on soil moisture data. Inoculated plants sustained yield levels with 13% lower water and fertilizer rates, the team reports. That equates to a 1.6% cost decrease, which the researchers calculate is six times more than the cost of inoculation.
