Project Overview
Commodities
- Nuts: chestnuts
Practices
- Crop Production: agroforestry, irrigation, water management
Proposal summary:
Steady slow irrigation is
generally the most optimal for plant growth, plant health, soil
health, erosion control, and other agricultural aspects.
Unfortunately the weather rarely rains in a steady slow stream;
instead, plants are frequently stressed or killed by too much or
too little water. Too much water can be somewhat controlled by
cover crops and buffer strips, but these techniques are not
widespread and can take time and money to develop. Too little
water can be somewhat remediated by irrigation, but current
irrigation methods can be expensive, complicated, and require
large amounts of water.
Our specific application requires
providing regular moderate amounts of water to newly planted
young chestnut trees. Current irrigation techniques are designed
for high density gardens or annual crop fields, but commercial
tree planting is done at large scale and low density (tens of
trees per acre). These tree plantings are better modeled as
discrete points that require water, rather than an entire field
that requires uniform irrigation. Thus most trees are watered by
hand using water from hoses and buckets with small holes to
slowly drip water into the ground, or with custom irrigation
setups grafted onto existing irrigation systems.
Project objectives from proposal:
Our solution is clay pots with
rain and dew catching systems. Pots have been used for thousands
of years as irrigation containers whose walls slowly transfer
water from the pot to the surrounding soil, autoregulate by
increasing irrigation in dry soil and decreasing irrigation in
wet soil, provide water more directly to roots, and can be easily
filled by hand. Their research has been restricted to biomes of
sandy soils in arid or semi arid climates, all unlike Iowa (see
for example “The auto-regulative capability of pitcher irrigation
system”, Abu-Zreig et al, 2006). Each pot will have a water
collector to catch and store rain and passively collect dew every
night. Dew varies greatly but may average 0.2 liters per square
meter per night (“A review: dew water collection from radiative
passive collectors to recent developments of active collectors”,
Khalil et al, 2015). This will reduce the amount of water and
labor required for irrigation and provide myriad other benefits,
all for no energy and no additional carbon footprint during
operation.
The trials of this research
project will use different configurations of pots and water
collectors to maximize data gained and quantify the influences of
the many variables. Pots will be manufactured in the shape of
cylinders with radius 1 foot, height 1 foot, and a small center
hole on top. They will be buried a couple inches deep near a
tree. Water collectors will be plastic sheeting in 3 foot by 3
foot squares that are secured and supported by four 2 foot high
poles, with one pole at each vertex of the square, to form an
inverted pyramid which rain and dew will trickle down the sides
of to be collected in the pot. A hole will be made in the
sheeting to fit the tree into.
10 pots and water collectors will
provide an experimental baseline. The other trials will provide
comparisons with modified configurations of 5 with an additional
dew condenser attachment, 5 with a larger water collector of 4
feet by 4 feet, 3 with no water collector, 2 sealed to not
collect water at all, and 5 buried on top of a small barrier
designed to restrict water flow more primarily to the
tree.
3 plastic pots impermeable to
water and with water collectors will be used as controls for rain
and dew to measure these as the water will be partially absorbed
and distributed in the trials. These plastic pots will be
paired and the amount of rain or dew caught will be
measured by weighing with scales.
For controls we will measure the
soil moisture of nearby areas of grass, mulch, and trees without
pots.
If rainfall is sufficient, no
external irrigation will be provided. If rainfall is
insufficient, external irrigation will be provided with equal
amounts of water in all cases in order to sustain the
trees.
Rainfall, humidity, and
temperature are key variables that will be measured locally using
appropriate instruments.
Our objective is to demonstrate
the viability of pots with water collectors by measuring
irrigation rate, dew collection rate, and soil moisture
dispersion rate in a wide variety of trials, control
configurations, and weather. The data will be collected during
the growing season of second half of April to October, and
analyzed and disseminated during the dormant season of November
to first half of April. Outreach discussing initial data will be
done after the first growing season and more comprehensively done
after the second growing season.