1. Soil moisture,
nutrients, and weeds –
we have the No-Till
situation
Olga Walsh, PhD
Cropping Systems Agronomist & Extension Specialist
Parma Research & Extension Center, Parma, ID
2. OUTLINE
• Tillage
• Dust bowl and soil erosion
• No-till:
• Adoption
• Soil moisture
• Nutrients (Carbon, Nitrogen)
• Weed control
***All processes are interconnected
3. TILLAGE
• Tillage = mechanical manipulation of soil for the
purpose of enhancing the growth of crops.
• Archaeologists discovered wooden plows which
were used in Egypt as early as 3000 B.C.
• Preparing an improved environment for seed
germination was the objective of soil tillage for
thousands of years.
Early wooden plow;
Egypt, 3000 BC
http://www.bae.uky.edu/lwells/BAE513/Lectures/Chap1new2.pdf; http://www.crustbuster.com/no-till-drills-and-planers
4. TO TILL OR NOT TO TILL?
• 1850-1900’s – transition from animal power to mechanical
• 1920’s – the Great DustBowl
• 1950’s – beginning of conservation tillage
• 1980’s – 50% of arable land in US is under conservation tillage
• Major drives: to reduce soil erosion and degradation and to reduce
energy inputs
http://www.kshs.org/p/forces-of-nature-part-3/16690; http://capita.wustl.edu/namaerosol/Dust%20Bowl%20map.htm
5. SOIL WIND EROSION
Wind erosion has
removed the surface soil
from this field, exposing
the less fertile subsoil
Eroding soil filling furrows;
Wheat plants blown out by a storm
http://www.weru.ksu.edu/new_weru/multimedia/storms/storms1.html
9. http://www.ringingcedarsofrussia.org/anastasia/ringing-cedars-settlements.html
NO-TILL:
• Apply herbicide
• Plant
• Apply herbicide
• Harvest
CONVENTIONAL TILL:
• Till with moldboard plow, burying up to 90% of residue
• Till with disk to smooth the ground
• Till with field cultivator to prepare the seedbed for
planting
• Till with harrows to smooth seedbed
• Plant
• Apply herbicides
• Till with row cultivator
• Harvest
CONVENTIONAL VS NO-TILL
12. SOIL MOISTURE
• No-till farming can be considered as the most important tool to
prevent loss of soil moisture, especially during the drought
conditions (Barb Stewart, state agronomist with the USDA-
Natural Resources Conservation Service (NRCS) in Iowa)
• Soil tillage reduces soil moisture in several ways:
• Residue prevents soil crusting due to rain drop effect
• Reduces water infiltration by breaking up the large pores in the
soil structure, which act as large diameter pipelines for water to
soak into the soil profile
• Removes residue through tillage => soil erosion => eroded
particles of soil clog the smaller pores => prevent infiltration =>
cause soil runoff.
14. SM: CONVENTIONAL VS NO-TILL
http://soil5813.okstate.edu/Articles/NT%20in%20Argentina%20-%20A.Bianchini%20-%20V3.pdf
15. NO-TILL SM FACTS
• Every tillage pass can cause available plant moisture to drop .25 inch.
• Crop residue moderates soil temperatures, reducing soil moisture
evaporation, especially in the top two inches.
• Corn stalks can help trap snow, which can add up to 2 inches of soil
moisture after snow melt in the spring.
http://www.nrcs.usda.gov/wps/portal/nrcs/detail/ia/home/?cid=nrcs142p2_011847;
http://www.prairiefirenewspaper.com/files/201004-no-till-chloe.jpg
16. RESIDUE AND WATER
• Effect of stubble height on soil water
content change from fall to spring for a
4-foot depth in wheat-fallow at Mandan,
North Dakota (Kanwar, R.S., A. Kumar, and
D. Baker. 1998)
18. ORGANIC CARBON
• Is a fraction of the soil solid components, crucial for soil
productivity
• Organic matter participates in the cycle of several nutrients, like
N and S, impacting in the soil chemical fertility
• Organic carbon enters the soil through the decomposition of
plant and animal residues, root exudates, living and dead
microorganisms, and soil biota.
• Indicator of soil quality
20. SOIL ORGANIC CARBON
• Soil organic matter
in the 0 to 8 inch soil depth,
6 to 10 years after the
conversion to no-till, Montana
• No-till systems maintain and
build soil organic matter
• The process requires
nitrogen!
http://store.msuextension.org/publications/AgandNaturalResources/EB0182.pdf
21. NITROGEN IN NO-TILL (N)
• To gain 1% SOM in the upper 6 inches of soil, it takes ~1,000 lb
N/a above crop need; N needs to be added over time, likely
decades.
• If no additional N added => lower crop yields due to inadequate N
=> less roots and stubble added to the soil => lower the amount of
SOM accumulation, reducing N mineralization => reduced available
N in future years
• Also: crop residue left on the surface affects soil temperature and
moisture content => affects N mineralization and efficiency of N
fertilizer use.
http://store.msuextension.org/publications/AgandNaturalResources/EB0182.pdf
23. N MANAGEMENT IN NO-TILL
• More N (~40 lb N/a) is required due to lower N mineralization rates
and greater potential for nutrient stratification.
• N rates need to be slightly increased for several years, depending
on the field, to maximize yield and build SOM to save on N in the
long-term. More soil water increases N availability due to
increased N mineralization
• On-farm studies showed that long-term no-till (>6 years) should get
50 lb N/a credit, due to improved N availability and plant/microbe
balance
http://store.msuextension.org/publications/AgandNaturalResources/EB0182.pdf
24. PRECISION WEED CONTROL
Background:
Cross and multiple herbicide-resistant weeds are evident in
Montana farm fields.
Herbicide resistance management programs often use multiple
modes of action, which involve additional cost.
WeedSeeker® sprayer could be a cost-effective technology for
precision weed control in chem-fallow.
Operates on differential red and near infrared light absorption by a
green plant relative to bare ground or residue cover and activates
a solenoid switch above a spray nozzle.
In collaboration with Prashant Jha, Weed Scientist, MSU
25. PRECISION WEED CONTROL
Objectives:
• Compare weed control efficacy
between WeedSeeker® and
conventional broadcast sprayer in
post-harvest wheat stubble.
• Determine the herbicide savings
using WeedSeeker® sprayer vs.
conventional broadcast sprayer.
26. PRECISION WEED CONTROL
Methods:
• Experimental Site: Southern Agricultural Research Center,
Huntley, MT; Year: 2013
• Target broadleaf weeds: Kochia, prickly lettuce
• Time of Application: Post-harvest wheat (15-30 cm-weed height)
• Sprayer: 5 foot, ATV-mounted, spray boom fitted with five
WeedSeeker® sprayer units equipped with flat-fan nozzles
spaced 12 in apart, to deliver 20 gal per ac
27. PRECISION WEED CONTROL
• Saved between 45 and 62 % in cost per ac
• WeedSeeker® technology is economically feasible to use high
rates of an herbicide or herbicide tank-mixtures.
• Cost-effective control of weed escapes and herbicide-resistant
weeds in chem-fallow/post-harvest wheat stubble.
• Greater environmental sustainability (less pesticide use per ac) at
the whole farm level.
29. ARGENTINA NO-TILL SUCCESS
- 96% less soil erosion.
- 66% less fuel use.
- Maintenance or improvement of the organic matter.
- Higher water use efficiency.
- Increase in soil fertility.
- Lower production costs.
- Higher production stability and higher yield potential.
31. THANK YOU!
Olga Walsh
Cropping Systems Agronomist and Extension
Specialist
Parma Research & Extension Center
owalsh@uidaho.edu
(208)722-6701
ID Crops & Soils blog: www.idcrops.blogspot.com
Twitter: @IDCrops
