Great opinion article by Francis Thicke and others!

Tom

 

 

-----Original Message-----
From: Laurel Hopwood <[log in to unmask]>
To: CONS-SPST-BIOTECH-FORUM <[log in to unmask]>
Sent: Fri, Dec 25, 2015 9:05 am
Subject: Organic farming can cut nitrate leaching in half

http://www.desmoinesregister.com/story/opinion/abetteriowa/2015/12/24/organic-farming-can-cut-nitrate-leaching-half/77774262/
Organic farming can cut nitrate leaching in half
by soil scientist and organic farmer Francis Thicke (and others). Email: 
[log in to unmask]
(edited)

Recent research published by Cynthia Cambardella and Dan Jaynes, USDA 
Agricultural Research Service in Ames and Kathleen Delate, Iowa State 
University in the journal “Sustainable Agriculture Research” 
demonstrated that a typical organic crop rotation reduced nitrate 
leaching from crop fields by nearly 50 percent, compared to the 
conventional corn and soybean rotation common in Iowa.
The researchers measured how much nitrate leached down through the soil 
profile and out through the field tile drainage systems, which drain 
into streams and rivers. Over three years, the conventional corn/soybean 
cropping system leached a total of 69.7 lb/acre of nitrate-nitrogen, 
compared to 35.1 lb/acre for the organic cropping system.

Certified organic production requires more diverse cropping systems. As 
in this field experiment, small grain crops (like oats, wheat and rye) 
and perennial crops (like alfalfa and forage grasses) are normally 
included in organic crop rotations. Perennial and small grain crops can 
be efficient scavengers of soil nitrate. Perennial crops have live roots 
in the ground all year long, compared to annual crops which have live 
roots in the ground for approximately five months of the year. Perennial 
crops provide uptake and recycling of nitrate and protection against 
nitrate leaching during times of the year when annual crops cannot.

Second, in conventional agriculture, nitrogen is supplied to crops in 
synthetic, mineral forms. Those forms become rapidly available for crop 
uptake, but are highly water soluble and susceptible to leaching when 
rainfall percolates through the soil profile. In organic farming 
systems, nitrogen is supplied to crops in organic forms — such as legume 
crops, compost or manure — which are incorporated into the soil. Organic 
forms of nitrogen are not immediately available for crop uptake or for 
leaching, but are released slowly throughout the growing season into 
mineral (plant-available) forms by soil microbes, matching the timing of 
crop needs for nitrogen during the growing season, thereby reducing the 
potential for nitrate leaching.

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