Effect of Tillage on Nitrogen Availability to Sugar Beets

Years 1 & 2

Amber Moore and David TarkalsonUniversity of Idaho – Twin Falls

USDA ARS - Kimberly

Introduction

• Introduction of Round-up Ready sugar beets– Weeds no longer controlled by cultivation

• Opportunities for conservation tillage methods, such as strip-till– No-till meets moldboard plow– Only disturbs portion of the soil that contains the

seed.• Estimated 1800 acres of strip-till sugarbeets in

Idaho in 2008

Introduction

• Advantages of strip till over moldboard plow– Reducing number of passes– Controls soil erosion– Water retention– Apply chemicals and fertilizers during tillage

Introduction

• Chisel plowing– Loosens the soil without inverting it– Residues are partially incorporated into the soil– Breaks into plow pan

http://www.maes.msu.edu/ressta/saginawvalley/Pic_Tour/14C23chisel_plow.jpg

Introduction

Concerns with strip till and chisel plowing Organic matter lying on surface, no longer fully

incorporated into the soil Sugar beets highly sensitive to N release rates and

release timing Will reduction of carbon and aeration/mixing slow

biological processes such as N mineralization? Will reduction of carbon lower C:N ratios, thus speeding

up N mineralization and slowing down immobilization? Release of residue N

Introduction

• Tillage timing– Fall tillage• Allows incorporated residues time to decompose

– Potentially less tie-up of N

– Spring tillage• Can apply fertilizers and pesticides while tilling (for strip

till)• Prevents soil erosion over winter (chisel plow and

moldboard plow)

Effect of Tillage on Nitrogen Availability to Sugar Beets

• Project goal - To determine the effect of tillage method and tillage timing on nitrogen available to sugar beets following a cereal crop

Experimental design

• Tillage study at USDA-ARS Kimberly– David Tarkalson and Dave Bjorneberg

• Three tillage methods– Strip till (ST)– Chisel plow (CP)– Moldboard plow (MP)

• Two tillage times– Fall and spring

• Five fertilizer N rates, including a control

Moldboard Plow

Chisel Plow

Strip Till

Year Tillage BeddingUAN application rate (lbs N/acre)

0 50 100 150 200----------lbs plant available N/acre---------------

2008

Strip tillage Fall 79.0 ab 102.7 ab 101.9 bc 154.7 186.3Spring 91.7 a 81.0 b 121.5 ab 179.7 188.8

Chisel PlowFall 66.2 ab 96.6 ab 156.8 a 143.8 164.7

Spring 59.7 b 88.0 ab 115.7 abc 146.2 169.6

Moldboard Plow

Fall 77.2 ab 143.5 a 138.8 ab 171.7 214.9Spring 63.1 b 69.4 b 77.3 c 119.2 108.8

P>0.05/LSD 26.9 57.4 44.1 NS NS

2009

Year Tillage BeddingUAN application rate (lbs N/acre)

0 50 100 150 200----------lbs plant available N/acre---------------

2008

Strip tillageFall 79.0 ab 102.7 ab 101.9 bc 154.7 186.3

Spring 91.7 a 81.0 b 121.5 ab 179.7 188.8

Chisel PlowFall 66.2 ab 96.6 ab 156.8 a 143.8 164.7

Spring 59.7 b 88.0 ab 115.7 abc 146.2 169.6

Moldboard Plow

Fall 77.2 ab 143.5 a 138.8 ab 171.7 214.9Spring 63.1 b 69.4 b 77.3 c 119.2 108.8

P>0.05/LSD 26.9 57.4 44.1 NS NS

2009

Strip tillageFall 103.7

Spring 100.8

Chisel PlowFall 90.2

Spring 97.5

Moldboard Plow

Fall 106.8Spring 134.8

P>0.05/LSD NS

Year Tillage BeddingUAN application rate (lbs N/acre)

0 50 100 150 200----------lbs plant available N/acre---------------

2008

Strip tillageFall 79.0 ab 102.7 ab 101.9 bc 154.7 186.3

Spring 91.7 a 81.0 b 121.5 ab 179.7 188.8

Chisel PlowFall 66.2 ab 96.6 ab 156.8 a 143.8 164.7

Spring 59.7 b 88.0 ab 115.7 abc 146.2 169.6

Moldboard Plow

Fall 77.2 ab 143.5 a 138.8 ab 171.7 214.9Spring 63.1 b 69.4 b 77.3 c 119.2 108.8

P>0.05/LSD 26.9 57.4 44.1 NS NS

2009

Strip tillageFall 103.7 95.5

Spring 100.8 127.7

Chisel PlowFall 90.2 102.8

Spring 97.5 111.8

Moldboard Plow

Fall 106.8 106.4Spring 134.8 101.1

P>0.05/LSD NS NS

Year Tillage BeddingUAN application rate (lbs N/acre)

0 50 100 150 200----------lbs plant available N/acre---------------

2008

Strip tillage Fall 79.0 ab 102.7 ab 101.9 bc 154.7 186.3

Spring 91.7 a 81.0 b 121.5 ab 179.7 188.8

Chisel PlowFall 66.2 ab 96.6 ab 156.8 a 143.8 164.7

Spring 59.7 b 88.0 ab 115.7 abc 146.2 169.6

Moldboard Plow

Fall 77.2 ab 143.5 a 138.8 ab 171.7 214.9

Spring 63.1 b 69.4 b 77.3 c 119.2 108.8P>0.05/LSD 26.9 57.4 44.1 NS NS

2009

Strip tillage Fall 103.7 95.5 126.2Spring 100.8 127.7 121.8

Chisel Plow Fall 90.2 102.8 132.7Spring 97.5 111.8 127.4

Moldboard Plow

Fall 106.8 106.4 128.5Spring 134.8 101.1 131.1

P>0.05/LSD NS NS NS

Year Tillage BeddingUAN application rate (lbs N/acre)

0 50 100 150 200----------lbs plant available N/acre---------------

2008

Strip tillageFall 79.0 ab 102.7 ab 101.9 bc 154.7 186.3

Spring 91.7 a 81.0 b 121.5 ab 179.7 188.8

Chisel PlowFall 66.2 ab 96.6 ab 156.8 a 143.8 164.7

Spring 59.7 b 88.0 ab 115.7 abc 146.2 169.6

Moldboard Plow

Fall 77.2 ab 143.5 a 138.8 ab 171.7 214.9Spring 63.1 b 69.4 b 77.3 c 119.2 108.8

P>0.05/LSD 26.9 57.4 44.1 NS NS

2009

Strip tillageFall 103.7 95.5 126.2 144.3 215.5

Spring 100.8 127.7 121.8 163.7 190.1

Chisel PlowFall 90.2 102.8 132.7 142.4 184.9

Spring 97.5 111.8 127.4 132.2 166.2

Moldboard Plow

Fall 106.8 106.4 128.5 137.0 144.0Spring 134.8 101.1 131.1 131.2 200.3

P>0.05/LSD NS NS NS NS NS

Figure 3. Effect of tillage treatment and timing for soil carbon content at a one-foot depth for a Portneuf silt loam at planting, averaged over 2008 and

2009 and over nitrogen rates. CP = Chisel plow, ST = Strip-till, MB = Moldboard plow.

2.49

2.41

2.372.35

2.33 2.32

2.20

2.25

2.30

2.35

2.40

2.45

2.50

2.55

% S

oil c

arb

on

Tillage method

a

ab

abab

b b

Conclusion

• It seems that tillage method and timing are more likely to impact nitrogen mineralization in growth limiting environments (lower N, higher C, etc.).

• Spring plowed and chisel-plowed soils show the greatest increase in carbon compared to fall plowed and moldboard or strip-tilled soils

Thank you!