The document summarizes findings from long-term trials comparing the effects of conventional, organic-legume, and organic-manure farming systems on water quality. Nitrate leaching was highest with synthetic fertilizer and raw manure applications, whereas compost reduced nitrate leaching by over half. Herbicides readily leached from conventional systems but not organic systems. Organic systems increased soil organic matter by up to 28% over 22 years, improving water percolation and yield under drought. Regenerative farming systems and practices like compost application were found to conserve and improve both surface and ground water quality.

1. Water Agriculture and You
Paul Hepperly, Rita Seidel, Christine Zeigler, and John Haberern
Abstract
Using The Rodale Institute® unique long term experimentation, The Farming Systems (FST)
and Compost Utilization (CUT) Trials, we evaluated how regenerative/organic farming systems
and practices influences water quality. Lysimeters, devices which collect water that passes
through the crop root zone, were used to measure agricultural water outputs which affect surface
and ground waters. Nitrate leaching was found in all organic and conventional systems and
practices but higher nitrate pulses were associated with soluble synthetic fertilizer and raw
manure than with compost applications. Although all fertilization strategies, i.e. synthetic
fertilizer, raw manure, and compost, optimized corn yield, only compost reduced nitrate leaching
over half compared to both fertilizer and manure applications. Corn herbicides atrazine and
metalachlor readily leached past the root systems in conventional corn and soybean production
but not in organic systems. Atrazine leaching consistently exceeded the 0.1ppb. This
concentration is proven to disrupt male amphibian sexual development. Occasionally atrazine
concentration exceeded 3 ppb, the EPA limit for atrazine in drinking water.
Regenerative/organic systems and practices increased the level of soil organic matter or soil
carbon (up to 28% in 22 years) leading to increased (up to 50% more) percolation of water.
Surface runoff decreases as water percolation improves. In drought years organic systems
produced higher corn and soybean yields (28 to 34%) based on better water delivery from the
improved soil organic matter content. Long term studies of regenerative/organic farming systems
and practices show their clear potential for conserving and improving surface and ground water
resource quality.
Background
Since 1981, The Rodale Institute® (TRI) has compared conventional and organic corn and
soybean production systems in its Farming Systems Trial for system effects on yields, economic
returns, and environmental performance (Petersen et al., 1999). In this trial Conventional corn
and soybean row crop rotation depends on synthetic fertilizer and herbicides applied according to
current recommendations of Pennsylvania State University Cooperative Extension Service
(CONV). In addition, to conventional corn and soybean system there are two organic
management systems compared. There are two organic systems. These are: 1) a cash grain corn,
soybean and wheat rotation with legume and grass cover crops to provide nitrogen and weed
suppression (ORG LEG). 2) a mixed farming system that uses manure and legume crops as crop
nutrient sources in a 5 year corn, soybean, silage corn, wheat, and hay rotation (ORG MAN).
Since 1993, in their Compost Utilization Trial, TRI investigators have compared the long term
effects of composts, manure, and conventional fertilizer on yield of corn, wheat and vegetables
as well as soil quality, farm economics, and environmental effects of these practices (Reider et
al., 2000).
In 1991, lysimeters, devices which collect water moving past the crop root zone were installed in
FST and in 1993 they were installed in CUT. From 1991 to 2003 samples were collected from 90

2. lysimeters 15 to 20 times per year giving thousands of water quality observations. Together these
important trials offer unique and valuable information on how agricultural practices impact water
quality.
Nitrate Leaching Findings
Twenty percent of the conventional corn and soybean row crop system samples exceeded the 10
ppm limit for healthy drinking water while only 10 and 16% of the organic manure or cash grain
systems exceeded the same limit.
Leached total nitrate for raw dairy manure, conventional synthetic fertilizer and broiler litter leaf
compost were 100, 75, and 33 lbs per acre, respectively, over the 1994 to 2003 time period.
Perentage of water samples exceeding 10 ppm Nitrate Nitrogen Limit in The Rodale Institute
Farming Systems Trial 1991 to 2003 Kutztown, Pennsylvania.
20
16
10
0 5 10 15 20 25
Conv. Corn and Soybean
Org. Legume Cash Grain
Org. Manure Mixed Crop
FarmingSystems
Percent Samples over 10 ppm Nitrate Nitrogen

3. Herbicide Leaching Findings
In the conventional corn and soybean production system all water samples exceeded the 0.1 ppb
level shown to cause sexual alterations in male frogs (Hayes et al 2002). In corn after corn
conventional plots leachates samples occasionally exceeded the 3 ppb allowable concentration
for municipal water set by USEPA. Metolachlor was also detected at 0.2 to 0.6 ppb range for
steady detection in conventional corn and soybean and occasionally peaked over 3 ppb similar to
atrazine. No sideward movement of herbicide was found into adjacent organic plots where
herbicides were never detected in leachate.
Soil Carbon Findings
From 1981 to 2002 increases in soil carbon were 8, 16 and 28% for the conventional corn and
soybean and organic legume and manure systems, respectively. In the CUT even higher
accumulation of soil carbon was found for compost but not for synthetic fertilizer or raw manure.
Soil carbon increases are associated with improved soil aggregation and water infiltration.
Organic systems improved percolation rates up to 50% in some cases. This meant lower runoff
and soil erosion.
Conclusions
100
75
33
0 10 20 30 40 50 60 70 80 90 100
Cumulative Nitrate Nitrogen Leached in Pounds per Acre
R
aw
D
airy
M
anure
Synthetic
Fertilizer
Broiler Litter Leaf C
om
post
N
utrientSources
Cumulative Nitrate Nitrogen Leaches 1993 to 2002 in the Compost Utilization Trial at The
Rodale Institute Kutztown, Pennsylvania.

4. Through sensible farm practices, farmers can improve water quality on their farms and for
surrounding areas.
Nutrient losses are found in many agricultural practices. However these losses are much less
with compost compared to raw manure and synthetic fertilizer.
Systems (mixed cropping) and practices (compost additions) can build soil carbon or organic
matter. This increases soil aggregation and soil water percolation. The result of this change is
increased aquifer recharge and reduced soil erosion losses.
Although all systems and practices produce similar high yield in absence of drought stress,
organic systems produced higher corn and soybean yields than conventional corn and soybean
row crops under drought.
In conventional farm systems, commonly used herbicides are transferred to soil and ground and
surface water. This danger is eliminated in organic production systems.