STRIP-TILL CORN RESPONSE TO DEEP-BANDED PLACEMENT OF PHOSPHORUS AND POTASSIUM. A Thesis. Submitted to the Faculty. Purdue University.

Transcription

1 i STRIP-TILL CORN RESPONSE TO DEEP-BANDED PLACEMENT OF PHOSPHORUS AND POTASSIUM A Thesis Submitted to the Faculty Of Purdue University By Matías Cánepa In Partial Fulfillment of the Requirements for the Degree Of Master of Science August 2007 Purdue University West Lafayette, Indiana

2 To Silvina and Fausto, my Family and Friends, for always give me reasons to believe ii

3 iii ACKNOWLEDGMENTS I would like to express deep gratitude to my major professor, Dr. Tony J. Vyn, for giving me the opportunity of an invaluable life experience. Also, I would like to thank Cathy Vyn for all her kind support during these two years. I am grateful to my Committee Members, Dr. Camberato, Dr. Nielsen and Dr. Reetz for always being there to help and encourage me all along the way. The Foundation for Agronomic Research, the Potash and Phosphate Institute, John Deere and the Department of Agronomy have been dedicated to providing the funding required to finish the research. I would like to thanks Terry West, Chris Boomsma, Judy Santini, Ken Scheeringa and the group of people that helped during summer for their effort and dedication to this project. I would specially like to thanks Fernando and Liliana García, Ignacio and Martín for all what they have done for me.

4 iv TABLE OF CONTENTS Page LIST OF TABLES... xi LIST OF FIGURES... xvi ABSTRACT... xxii CHAPTER 1. STRIP-TILL CORN RESPONSE TO DEEP BANDED PLACEMENT OF PHOSPHORUS AND POTASSIUM, STUDY... 1 Abstract... 1 General Introduction and Objectives... 4 Materials & Methods Site description Field history Experimental design and treatments Cultural practices Soil measurements Weather characterization Plant measurements Statistical analysis Results & Discussion Soil Measurements Crop growth and developmental responses (2005) I) Plant height and biomass at V4 and V II) Early season nutrient uptake III) Plant measurements during reproductive stages IV) Mid-late season nutrient uptake V) Corn Grain Yield Crop growth and developmental responses (2006) I) Plant height and biomass at V4 and V II) Early season nutrient uptake III) Plant measurements during reproductive stages IV) Mid-late season nutrient uptake V) Corn Grain Yield Conclusions... 89

5 v Page CHAPTER 2. STRIP-TILL CORN RESPONSE TO DEEP BANDED PLACEMENT OF PHOSPHORUS AND POTASSIUM, STUDY Abstract General Introduction and Objectives Materials & Methods Site description Field history Experimental design and treatments Cultural practices Soil measurements Weather characterization I) Mean air temperature (ºC) II) Mean monthly precipitation (mm) and soil moisture content (mm) Plant measurements Statistical analysis Results & Discussion General Considerations Odd-number years: 2001, 2003 and I) Soil measurements II) Crop growth, development and nutritional status at vegetative stages III) Crop growth, development and nutritional status at reproductive stages IV) Corn grain yield Even-numbered years: 2002, 2004 and I) Soil measurements II) Crop growth, development and nutritional status at vegetative stages III) Crop growth, development and nutritional status at vegetative stages IV) Corn grain yield Effect of weather-related variables on corn grain yield ( ) and the relative yield response of corn to Broadcast or Banded application of P and K Conclusions CHAPTER 3. GENERAL DISCUSSION LIST OF REFERENCES APPENDICES Appendix A: Materials & Methods ( ) Appendix A-1. Total applied amount of N(a), P(b) and K(c) by fertility treatment in 2005 and Appendix A-2. Plant population by treatment in 2005 and

6 vi Page APPENDICES Appendix B: Soil test results ( ) Appendix B-1. Hybrid treatment mean soil test results at three soil depth intervals for Appendix B-2. Fertility treatment mean soil test results at three soil depth intervals for Appendix B-3. Hybrid treatment mean soil test results at three soil depth intervals for Appendix B-4. Fertility treatment mean soil test results at three soil depth intervals for Appendix B-5. Hybrid treatment effect on mean P and K stratification ratios (0-10/10-20 cm) in Appendix C: Crop growth and nutritional parameters for Appendix C-1. Biomass K concentration (%), by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval Appendix C-2. Biomass K concentration (%), by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval, Appendix C-3. SPAD readings taken at the ear leaf (R3), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix C-4. SPAD readings taken at the ear leaf (R3), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix C-5. SPAD readings taken at the fourth leaf (R3), by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval, Appendix C-6. SPAD readings taken at the fourth leaf (R3), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix C-7. SPAD readings taken at the fourth leaf (R3), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix C-8. Stalk diameter (mm) measured at maturity (R6), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix C-9. Ear leaf-p (%), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix C-10. Ear leaf-p (%), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix C-11. Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval, Appendix C-12. Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval, Appendix C-13. Grain P concentration (%), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval,

7 vii Page APPENDICES Appendix C-14. Grain P concentration (%), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix C-15. Corn grain yield (kg ha -1 ), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix C-16. Corn grain yield (kg ha -1 ), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix C-17. Corn grain yield (kg ha -1 ), by fertility treatment, relative to plant height (cm) measured at silking (R1), Appendix C-18. Corn grain yield (kg ha -1 ), by fertility treatment, relative to stalk diameter (mm) measured at maturity (R6), Appendix D: Crop growth and nutritional parameters for Appendix D-1. Plant heights (cm) measured at V4, by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval, Appendix D-2. Plant heights (cm) measured at V4, by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval, Appendix D-3. Plant heights (cm) measured at V4, by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix D-4. Plant heights (cm) measured at V4, by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix D-5. Fertility treatment effect on ear leaf SPAD measurements (R1, R3 and R5) in Appendix D-6. Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval in Appendix D-7. Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval in Appendix D-8. Corn grain yield (kg ha -1 ), by fertility treatment, relative to stalk diameter (mm) measured at the V8 growth stage, Appendix D-9. Corn grain yield (kg ha -1 ), by fertility treatment, relative to stalk diameter (mm) measured at silking (R1), Appendix D-10. Corn grain yield (kg ha -1 ), by fertility treatment, relative to stalk diameter (mm) measured at maturity (R6), Appendix E: Materials & Methods ( ) Appendix E-1. Plant population by treatment in 2005 and Appendix F: Soil test results for 2001, 2003 and Appendix F-1. Fertility treatment mean soil test results at three soil depth intervals for OM, ph and CEC (a), and P and K (b) in 2001, 2003 and Appendix F-2. Hybrid treatment mean soil test results at 0-10 (a), (b) and (c) cm soil depth intervals for 2001, 2003 and

8 viii Page APPENDICES Appendix F-3. Soil-P and -K coefficient of variation at the 0-20 cm soil depth interval of fertility treatment plot means in 2001, 2003 and Appendix F-4. Soil-P and -K range at the 0-20 cm soil depth interval of fertility treatment plot means in 2001, 2003 and Appendix G: Crop growth and nutritional parameters for 2001, 2003 and Appendix G-1. Hybrid treatment mean plant heights in 2001 (V6) and 2005 (V4, V10) Appendix G-2. Fertility and hybrid treatment mean biomass N, P and K concentration in 2001, 2003 and Appendix G-3. Biomass K concentrations (%), by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval, Appendix G-4. Biomass K concentrations (%), by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval, Appendix G-5. Hybrid treatment effect on mean N, P and K biomass concentrations in Appendix G-6. Hybrid treatment effect on mean total N, P and K uptake in 2001, 2003 and Appendix G-7. Ear leaf-p (%), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix G-8. Ear leaf-p (%), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix G-9. Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval, Appendix G-10. Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval, Appendix G-11. Fertility treatment mean grain nutrient concentration in 2001 and Appendix G-12. Grain P concentrations (%), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix G-13. Grain P concentrations (%), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix G-14. Hybrid treatment effect on mean total crop N, P and K removal in 2001, 2003 and Appendix G-15. Hybrid treatment effect on yields (kg ha -1 ) in 2001, 2003 and Appendix G-16. Corn grain yield (kg ha -1 ), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix G-17. Corn grain yield (kg ha -1 ), by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval,

9 ix Page APPENDICES Appendix H: Soil-test results for 2002 and Appendix H-1. Fertility treatment mean soil test results at three soil depth intervals for OM, ph and CEC (a), and P and K (b) in 2002 and Appendix H-2. Fertility treatment mean coefficient of variation and range for P and K at the 0-20 cm soil depth interval in 2002 and Appendix H-3. Hybrid treatment mean soil test results at 0-10, and cm soil depth intervals in 2002 and Appendix I: Crop growth and nutritional parameters for 2002, 2004 and Appendix I-1. Plant heights (cm) measured at V4 growth stage, by fertility treatment, relative to soil exchangeable K (ppm) in the cm soil depth interval, Appendix I-2. Plant heights (cm) measured at V4 growth stage, by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval, Appendix I-3. Plant heights (cm) measured at V4 growth stage, by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix I-4. Plant heights (cm) measured at V4 growth stage, by fertility treatment, relative to soil available P (ppm) in the cm soil depth interval, Appendix I-5. Biomass P concentrations (%), by fertility treatment, relative to soil available P (ppm) at the cm soil depth interval, Appendix I-6. Hybrid treatment effect on biomass nutrient concentration (%) in 2002 (V4-V5) and 2006 (V8) Appendix I-7. Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) at the cm soil depth interval, Appendix J: Effect of weather-related variables on corn grain yield ( ) and the relative yield response of corn to Broadcast or Banded application of P and K. 253 Appendix J-1. Annual average corn grain yields (kg ha -1 ), from the fertilized treatments, relative to soil moisture content (%) at the cm soil layer for August, ( ) Appendix J-2. Annual average corn grain yields (kg ha -1 ), from the fertilized treatments, relative to soil moisture content (%) at the cm soil layer for June+July, ( ) Appendix J-3. Average annual corn grain yields (kg ha -1 ), from fertilized treatments, relative to the stress factor of June, ( ) Appendix J-4. Annual average corn grain yields (kg ha -1 ), from fertilized treatments, relative to the cumulative stress factor of June+July, ( ) Appendix J-5. Ratio of Broadcast P+K:Banded P+K annual average grain yields relative to soil moisture content for June+July at the 0-15 cm soil layer, ( )

10 x Page APPENDICES Appendix J-6. Ratio of Broadcast P+K:Banded P+K annual average grain yields relative to soil moisture content for June+July at the cm soil layer, ( ) Appendix J-7. Ratio of Broadcast P+K:Banded P+K annual average grain yields relative to the combined stress factor for June+July, ( ) Appendix J-8. Ratio of Broadcast P+K:Banded P+K and Fertilized treatments annual average grain yields relative to the stress factor of June+July, ( )

11 xi LIST OF TABLES Table Page Table 1-1. Fertility treatment effect on mean soil test results at the 0-10 and cm soil depth intervals in Table 1-2. Fertility treatment effect on mean P and K stratification ratios (0-10/10-20 cm) in Table 1-3. Fertility treatment mean soil test results at the 0-10 and cm soil depth intervals in Table 1-4. Fertility treatment effect on coefficient of variation (CV), minimum and maximum values for available P (a) and exchangeable K (b) at the 0-20 cm depth in 2005 and Table 1-5. Fertility treatment effect on mean plant height (V4 ( ), V10 (*) ) in Table 1-6. Hybrid and broadcast K treatment effects on plant height (V4 ( ), V10 (*) ) means in Table 1-7. Fertility and hybrid treatment effects on aboveground biomass (*) (V10 ( ) ) means in Table 1-8. Fertility treatment effect on biomass nutrient concentrations (*) (V10) means in Table 1-9. Hybrid treatment influence on biomass nutrient concentrations (*) (V10) means in Table Fertility and hybrid treatment effects on total nutrient uptake (*) (V10) means in Table Fertility, hybrid and broadcast K split-split treatment means for plant heights (R1) in Table Fertility treatment means for SPAD (R1, R3, R5) measurements in

12 xii Table Page Table Hybrid and broadcast K treatment means for SPAD measurements (R1, R3 and R5) in Table Fertility treatment effect on mean stalk diameters at R1 ( ) and R Table Hybrid treatment means for stalk diameter (a) at R1 and R6, and (b) their interaction with broadcast K at R6 in Table Broadcast K treatment means for stalk diameter at R1 ( ) and R6 in Table Fertility (a) and hybrid (b) interactions with broadcast K for grain moisture content in Table Fertility and hybrid treatment means for ear leaf nutrient concentration (*) (R1) in Table Fertility, hybrid and broadcast K split-split treatment means for grain nutrient concentration in Table Fertility, hybrid and broadcast K split-split treatment means for crop nutrient removal in Table Fertility, hybrid and broadcast K split-split treatment means for corn grain yields in Table Fertility treatment plant height (V4 ( ), V8 (*) ) means in Table Hybrid and broadcast K treatment plant height (V4 ( ), V8 (*) ) means in Table Fertility, hybrid and broadcast K split-split treatment means for aboveground biomass (*) and stalk diameter (V8) in Table Fertility treatment means for biomass nutrient concentration (*) and total plant uptake (*) (V8) in Table Hybrid treatment means for biomass nutrient concentration (*) and total plant uptake (*) (V8) in Table Fertility (a) and hybrid (b) interactions with broadcast K for plant height at the R1 stage in

13 xiii Table Page Table Fertility treatment means for SPAD measurements at the fourth leaf (R1 ( ), R3) in Table Hybrid and broadcast K treatment means for ear and fourth leaf SPAD readings (R1, R3 and R5) in Table Fertility and hybrid interaction effects on stalk diameter at the R1 stage in Table Fertility treatment means for stalk diameter measurements (R6) in Table Hybrid and broadcast K treatment means for stalk diameter measurements (R1, R6) in Table Fertility and hybrid interaction effects with broadcast K on grain moisture contents in Table Fertility and hybrid treatment effects on mean ear-leaf nutrient concentrations (*) (R1) in Table Fertility, hybrid and broadcast K split-split treatment means for grain nutrient concentration in Table Fertility, hybrid and broadcast K split-split treatment means for crop nutrient removal in Table Fertility and broadcast K treatment means for corn grain yield (kg ha -1 ) in Table Hybrid treatment means for corn grain yield (kg ha -1 ) in Table 2-1. Hybrids utilized during this study and their specific characteristics Table 2-2. Total amount of N (a), P (b) and K (c) applied from starter and treatment application for each year of the study Table 2-3. Fertility treatment effect on mean soil test results at the 0-10 and cm soil depth intervals in Table 2-4. Fertility treatment effect on P and K stratification means (0-10/10-20 cm) for 2001, 2003 and

14 xiv Table Page Table 2-5. Fertility treatment effect on mean plant heights in 2001 (V6) and 2005 (V4, V10) Table 2-6. Fertility and hybrid treatment effects on mean aboveground biomass in 2001, 2003 and Table 2-7. Fertility treatment effect on mean N, P and K biomass concentrations in Table 2-8. Fertility treatment effect on mean total N, P and K uptake in 2001, 2003 and Table 2-9. Fertility and hybrid treatment effects on mean plant heights (R1) in Table Fertility (a) and hybrid (b) treatment effects on mean ear-leaf N, P and K concentrations sampled at silking (R1) in 2003 and Table Fertility treatment effect on mean grain nutrient concentrations in Table Hybrid treatment effect on mean N, P and K grain concentration in 2001, 2003 and Table Fertility treatment effect on mean total crop N, P and K removal in 2001, 2003 and Table Fertility treatment effect on yields (kg ha -1 ) in 2001, 2003 and Table Fertility treatment effect on mean soil-p and -K result at the 0-10 and cm soil depth interval in 2002 and Table Fertility treatment in soil-p and -K stratification means (0-10/10-20 cm) in 2002 and Table Fertility treatment effect on mean plant heights (V4, V8) in Table Fertility and hybrid treatment mean plant aboveground biomass (V4, V8) in 2002 and Table Fertility treatment effect on mean biomass N, P and K concentrations (%) in 2002 (V4-V5) and 2006 (V8)

15 xv Table Page Table Fertility (a) and hybrid (b) treatment effects on mean total N, P and K uptake at V4-V5 and V8 in 2002 and 2006, respectively Table Fertility and hybrid effects on plant height at silking (R1) in Table Fertility treatment effect on mean ear leaf N, P and K concentration (%) sampled at (R1) in Table Fertility and hybrid treatment effects on mean grain N, P and K concentration (%) in 2002 and Table Fertility and hybrid treatment effects on mean crop N, P and K removal (kg ha -1 ) in 2002 and Table Fertility (a) and hybrid (b) treatment effects on mean grain yield (kg ha -1 ) in 2002, 2004 and

16 xvi LIST OF FIGURES Figure...Page Figure 1-1. Monthly mean air temperature (ºC) for 2005 and 2006 compared to a 30-year normal ( ) Figure 1-2. Monthly precipitation (mm) for 2005 and 2006 compared to a 30-year normal ( ) Figure 1-3. Soil moisture content at the 0-15 and cm soil depth interval, daily rainfall and the stress factor for the period from planting tov10 and the corresponding SPI index for each week of the growing season in Figure 1-4. Soil moisture content at the 0-15 and cm soil depth interval, daily rainfall and the stress factor for the period V10-R5 and the corresponding SPI index for each week of the growing season in Figure 1-5. Soil moisture content at the 0-15 and cm soil depth interval, daily rainfall and the stress factor for the period from planting to V8 in Figure 1-6. Soil moisture content at the 0-15 and cm soil depth interval, daily rainfall and the stress factor for the period from V8 to R5 in Figure 1-7. Biomass P concentration (%), by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval (2005) Figure 1-8. Biomass K concentration (%), by fertility treatment, relative to available K (ppm) in the 0-10 cm soil depth interval, Figure 1-9. SPAD readings at the ear leaf (R3), by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval, Figure Stalk diameter measurement (mm) measured at maturity (R6), by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval,

17 xvii Figure Page Figure Ear leaf-p (%), by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval, Figure Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) in the 0-10 cm soil depth interval, Figure Grain P concentration (%), by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval, Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval, Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to ear leaf P (%) sampled at silking (R1), Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to grain P concentration (%), Figure Plant heights (cm) taken at the V4 growth stage, by fertility treatment, relative to soil exchangeable K (ppm) in the 0-10 cm soil depth interval, Figure Biomass K concentration (%), by fertility treatment, relative to soil exchangeable K (ppm) in the 0-10 cm soil depth interval, Figure Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) in the 0-10 cm soil depth interval in Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to soil exchangeable K at the 0-10 cm soil depth interval, Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to aboveground biomass K concentration (%) measured at the V8 growth stage, Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to ear leaf K concentration (%) measured at silking (R1) growth stage, Figure 2-1. Monthly mean air temperatures (ºC) for compared to a 30- year normal ( ) Figure 2-2. Monthly mean air temperature (ºC) for compared to a 30- year normal ( )

18 xviii Figure Page Figure 2-3. Monthly precipitation (mm) for compared to a 30-year normal ( ) Figure 2-4. Monthly precipitation (mm) for compared to a 30-year normal ( ) Figure 2-5. Soil moisture content at the 0-15 and cm soil depth interval, daily rainfall and the stress factor for the period from planting to 30 days after silking and the correspondent SPI index for each week of the growing season in Figure 2-6. Soil moisture content at the 0-15 and cm soil depth interval, daily rainfall and the stress factor for the period from planting to 30 days after silking and the correspondent SPI index for each week of the growing season in Figure 2-7. Soil moisture content at the 0-15 and cm soil depth interval, daily rainfall and the stress factor for the period from planting to 30 days after silking and the correspondent SPI index for each week of the growing season in Figure 2-8. Soil moisture content at the 0-15 and cm soil depth interval, daily rainfall and the stress factor for the period from planting to 30 days after silking and the correspondent SPI index for each week of the growing season in Figure 2-9. Soil moisture content at the 0-15 and cm soil depth interval, daily rainfall and the stress factor for the period from planting to 30 days after silking and the correspondent SPI index for each week of the growing season in Figure Soil moisture content at the 0-15 and cm soil depth interval, daily rainfall and the stress factor for the period from planting to 30 days after silking and the correspondent SPI index for each week of the growing season in Figure Biomass P concentration (%), by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval (2005) Figure Biomass K concentration (%), by fertility treatment, relative to soil exchangeable K (ppm) in the 0-10 cm soil depth interval, Figure Ear leaf-p (%), by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval, Figure Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) in the 0-10 cm soil depth interval,

19 xix Figure Page Figure Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) in the 0-10 cm soil depth interval, Figure Grain P concentration (%), by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval, Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to V6 plant height (cm), Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to grain P concentration (%), Figure Corn grain yield (kg ha), by fertility treatment, relative to grain K concentration (%), Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to plant height (cm) sampled at silking (R1), Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to soil available P (ppm) in the 0-10 cm soil depth interval, Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to ear leaf P (%) sampled at silking (R1), Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to grain P (%) sampled at silking (R1), Figure Plant heights (cm) measured at V4 growth stage, by fertility treatment, relative to soil exchangeable K (ppm) in the 0-10 cm soil depth interval, Figure Biomass P concentration (%), by fertility treatment, relative to soil available P (ppm) at the 0-10 cm soil depth interval, Figure Biomass K concentration (%), by fertility treatment, relative to soil exchangeable K (ppm) at the cm soil depth interval, Figure Biomass K concentration (%), by fertility treatment, relative to soil exchangeable K (ppm) at the 0-10 cm soil depth interval, Figure Ear leaf-k (%), by fertility treatment, relative to soil exchangeable K (ppm) at the 0-10 cm soil depth interval,

20 xx Figure Page Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to soil exchangeable K (ppm) at the 0-10 cm soil depth interval, Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to biomass K concentration (%) sampled at V8, Figure Corn grain yield (kg ha -1 ), by fertility treatment, relative to ear leaf K concentration (%) sampled at R1, Figure Annual average corn grain yields (kg ha -1 ), from the fertilized treatments, relative to the total rainfall (mm) for the period June+July+August, ( ) 179 Figure Annual average corn grain yields (kg ha -1 ), from the fertilized treatments, relative to the total rainfall (mm) for the period June+July, ( ) Figure Annual average corn grain yields (kg ha -1 ), from the fertilized treatments, relative to soil moisture content (mm) at the cm soil layer for July, ( ) Figure Annual average corn grain yields (kg ha -1 ), from the fertilized treatments, to the stress factor of July, ( ) Figure Ratio of Broadcast P+K:Banded P+K annual average grain yields relative to the total amount of rainfall (mm) between fertilizer application and planting, ( ) Figure Ratio of Broadcast P+K:Banded P+K annual average grain yields relative to the difference in monthly rainfall (mm) for the period for June versus July, ( ) Figure Ratio of Broadcast P+K:Banded P+K annual average grain yields relative to the difference in number of rainfall events (>10 mm) between June and July, ( ) Figure Ratio of Broadcast P+K:Banded P+K grain yield relative to soil moisture content for June at the 0-15 cm soil layer, ( ) Figure Ratio of Broadcast P+K:Banded P+K annual average grain yields relative to soil moisture content for June at the cm soil layer, ( ) Figure Ratio of Broadcast P+K:Banded P+K annual average grain yield relative to the stress factor of June, ( )

21 xxi Figure Page Figure Ratio of Broadcast P+K:Banded P+K annual average grain yield relative to the stress factor of July, ( ) Figure Ratio of Broadcast P+K/Banded P+K and Fertilized treatments annual average grain yield relative to the stress factor of June, ( ) Figure Ratio of Broadcast P+K/Banded P+K and Fertilized treatments annual average grain yield relative to the stress factor of July, ( )

22 xxii ABSTRACT Cánepa, Matías. M.S., Purdue University, August 2007, Strip-till Corn Response to Deep Banded Placement of Phosphorus and Potassium. Major Professor: Dr. Tony J. Vyn Deep-banded application of phosphorus (P) and potassium (K) fertilizers performed with strip tillage prior to planting corn might be a viable alternative to address some of the current concerns related to vertical nutrient stratification and possible lessthan-optimum corn yields in high yield production systems with conservation tillage. This two-year (2005 and 2006) experiment investigated the effect of deep-banded (15-18 cm) applications of P and K fertilizers, alone or in combination, compared to a broadcast P and K application and a check treatment on strip-till corn growth, nutrient uptake and yield following no-till soybean on a dark prairie soil near West Lafayette, IN. The experiments were designed to determine the possible interacting influences of two corn hybrids (main factor), five P and K placement treatments (split factor), and presence or absence of additional broadcast K fertilization for the prior soybean crop (split-split factor) on subsequent corn response. Generally, taller corn plants with wider stalks and higher plant nutrient concentrations of K and (or) P were characteristics of split-treatment or split-split treatments that added K fertilizer. Corn following deep-banded P and K yielded significantly more than the check but less than broadcast P+K in 2005 when

23 xxiii mean yields ranged from to Mg ha -1, but deep-banded P+K yielded similar to broadcast P+K, although again more than the check, when mean yields ranged from to Mg ha -1 in The relative yield advantage of broadcast over deepbanded application of P and K was correlated to rainfall and simulated estimates of plantavailable soil moisture at discrete depth intervals during June and July for 2005 and 2006 as well as in earlier years ( ) of essentially the same study at the same location. However, significant differences among fertility treatments in inherent soil available P and exchangeable K concentrations (due in part to accumulated fertilizer applications over time) plus numerous positive regression relationships between corn response parameters and variable soil-test P and K concentrations at the plot level constrained differentiation of fertilizer placement effects on corn growth and nutrient uptake. There was no evidence of a hybrid-specific response to P and K fertilizer placement. In these production systems involving intensive input applications for well above-average yield goals, continued deep-banded application of P and K fertilizers was generally not superior to broadcast application in terms of strip-till corn growth responses, plant nutrient concentrations, or final yields.

24 1 CHAPTER ONE STRIP-TILL CORN RESPONSE TO DEEP BANDED PLACEMENT OF PHOSPHORUS AND POTASSIUM, STUDY. Abstract Deep-banded application of phosphorus (P) and potassium (K) fertilizers performed with strip tillage prior to planting corn might be a viable alternative to address some of the current concerns related to probable nutrient stratification and possible lessthan-optimum corn yields in high yield production systems using conservation tillage. This two-year (2005 and 2006) experiment investigated the effect of deep-banded (15-18 cm) application of P and K fertilizers, alone or in combination, compared to that of a broadcast application and a control treatment on corn growth, nutrient uptake and yield in a strip-till corn production system following no-till soybean. The experiments were designed to determine the possible interacting influences of two corn hybrids (main factor), five P and K placement treatments (split factor) and presence or absence of additional broadcast K fertilization for the prior soybean crop (split-split factor) on subsequent corn response. Placement treatments included Broadcast P+K, Deep-banded P+K, Deep-Banded P alone, Deep-Banded K alone and Check. These five fertility placement treatments had also been evaluated on the 2005 site in 2003, and on the 2006 site in both 2002 and Soil-test P concentrations from samples collected between corn rows to a 20-cm depth after planting averaged 23 ppm in 2005 and much higher

25 2 (109 ppm) in 2006; soil-test K concentrations averaged 134 ppm in 2005 and 183 ppm in Most positive responses in corn growth, nutrient uptake, and yield relative to control plots (those without fertilizer P or K) occurred in treatments that built up the available potassium (K) supply regardless of fertilizer placement. Generally, taller plants with wider stalks and higher plant nutrient concentrations of K and (or) P were characteristics of split-treatment or split-split treatments which added K fertilizer. The broadcast application of P and K was the treatment most likely to enhance corn growth, macro-nutrient concentrations and yield while deep-banded placement of K, alone or in combination with P, also frequently improved corn performance and macronutrient concentrations relative to the control. Corn following Deep-banded P and K yielded significantly more than Check but less than Broadcast P+K in 2005 when mean yields ranged from to Mg ha -1, but Deep-banded P+K yielded similar to Broadcast P+K, although again more than Check, when mean yields ranged from to Mg ha -1 in Either the banded application of P alone or the Control treatment resulted in the poorest corn performance during both years of the study. However, significant differences among fertility treatments in inherent soil available P and exchangeable K test levels (due in part to accumulated fertilizer applications over time) plus numerous positive regression relationships between corn response parameters and plot-to-plot spatial variability in soil-test P and K concentrations diminished the possibility of distinguishing the genuine effects of fertilizer placement on corn growth and nutrient uptake. Drought stress episodes during the period of rapid plant uptake for K in both growing seasons seemed to enhance corn response to K fertilizer applications.

26 3 Accordingly, the sub-treatment that consisted of an additional broadcast application of K in the prior soybean crop also promoted corn development (although not always in a significant manner). Furthermore, there was no evidence of a hybrid-specific response to P and K fertilizer placement (whether broadcast or deep-banded, alone or in combination). In high fertility soils where intensive use of inputs were applied aiming for above average yields, deep-banded application of P and K fertilizers resulted in similar corn development rates and nutritional status, and either similar or slightly reduced grain yields, compared to that of a broadcast application of the same nutrients.

27 4 General Introduction and Objectives Conservation tillage systems like no-till arose as a partial solution to the sustainability challenge that field crop production with conventional tillage systems posed for agriculture. Reduced soil erosion, conservation of soil moisture and other operational advantages savings in time, fuel costs, machinery maintenance, and labor were benefits that fostered conservation tillage adoption by North American farmers between the 1980 s and mid-90 s. However, these tillage systems resulted, over time, in a completely new soil environment for field crop production. The no-till system altered soil properties and nutrient availability factors, consequently modifying corn response to management practices as well as the interaction between them and prevailing weather conditions. Higher soil moisture contents (Kladivko, 1986; Cox et al. 1990), reduced soil temperatures (Dwyer et al. 1995, Chassot et al. 2001), increased soil mechanical resistance (Barber 1971), and both horizontal and vertical phosphorus (P) and potassium (K) stratification (Crozier et al., 1999; Robbins and Voss, 1991; Mackay et al., 1987; Holanda, 1998; Vyn et al., 2002) were observed as common features characterizing these new reduced-tillage systems. From the corn farmer s perspective, a perception of reduced early growth, lower and less stable yields together with uncertainties about proper fertilizer management were critical factors contributing to uncertainty about the feasibility of continuous no-till production. Various studies have shown that strip tillage tillage of a band in the crop row approximately cm wide and cm deep - is a viable option to overcome some of the limitations associated with no-till (Griffith et al., 1973; Vyn and Raimbault, 1992).

28 5 This reduced tillage system leaves residue undisturbed in the interrow area, improves to some extent the seedbed environment for early corn growth, and was seen to achieve corn yield results comparable to conventional tillage -and occasionally superior to no-till (Vyn and Raimbault, 1992; Opoku et al., 1997). However, strip-till combined with broadcast application of non-nitrogen fertilizers (the most common method throughout the Corn Belt region), can conceivably increase vertical fertilizer stratification, mainly for less mobile nutrients such as phosphorus (P) and potassium (K), and have a detrimental effect on corn nutrient uptake, development and grain yield. Although the most optimum management for fertilizer placement for strip-till is still unknown, this tillage system might be advantageous due to simultaneously permitting the performance of the tillage operation and deep banding of fertilizers like P and K to less enriched soil depths than are likely at the surface. A linear increase in corn yield of about 109 kg ha -1 yr -1 since 1950 and declining P and K application rates since 1980 contributes to the need for more efficient fertilizer application methods (Dobermann, 2001). The latter trend plus the occurrence of more pronounced soil P and K stratification reinforces the need for better fertilizer management practices. Deep banding of P and K fertilizers in strip-tilled fields may offer several advantages. A more concentrated form of the fertilizer in the band than with broadcasting without incorporation might improve P and K availability as a consequence of reducing the degree of fertilizer adsorption by the soil constituents, keeping it more readily available to plant roots. Also, the closeness of the enriched deep band to the developing root system would promote early root growth and development and enhance plant P and

29 6 K uptake (Anghinoni and Barber, 1980a and b). Furthermore, deep banding might be advantageous due to vertical positional factor of the enriched deep band relative to roots at a depth where these nutrient concentrations are usually low. Other possible advantages of deep banding of fertilizers are the reduced dependence of plant nutrient uptake on soil moisture content and soil temperature condition near the soil surface factors closely associated with nutrient availability and root activity- and a higher recovery of applied fertilizer. Furthermore, systematic deep banding of P and K in the same row strip would build soil-test levels and increase the soil-fertilized volume in that zone, and consequently, improve fertilizer use efficiencies due to reduced nutrient adsorption and maximized nutrient uptake. Most of fertilizer rates and management recommendations were developed for conventional tillage systems and have not been adapted to current crop rotations involving reduced tillage corn production using higher yielding corn hybrids planted at increased populations. Corn P and K nutritional needs for these new cropping systems may not be adequately diagnosed and supplied based on inherent soil fertility in fields, soil sampling protocols, or fertilizer rates refined for conventional tillage production systems. Also, the fact that K has higher diffusion rates than P makes it more prone to migrate deeper into the soil profile and to have reduced residual effect from previous fertilizer applications than P. In view of this, and together with the high K influx requirement of young corn plants (Mengel and Barber, 1974) and steadily increasing corn grain yields, it is possible that the biannual K application strategy adopted by most farmers for the corn-soybean rotation may not sufficiently cover the corn crop nutritional

30 7 requirement. The need to reinforce K fertilization for the corn-soybean rotation might be achieved by an additional broadcast application of K on the soybean crop. Additionally, corn responses to tillage and fertilization management practices might be hybrid-specific. Several studies have shown that corn hybrids may be distinctive regarding morphological and physiological traits that are going to influence and determine the ability of corn plants to take up and utilize P and K. Root characteristics such as root surface area, root length and root hair volume, determine the plant s potential ability for P and K acquisition; these root factors all show high hybrid variability. Schenk and Barber (1979) found significant differences among five evaluated genotypes in corn root length, mean root radius and root surface per unit of shoot weight. Allan et al. (1997) also found differences in hybrid root architecture, basically in the amount of root length and the depth of root activity that led to differences in K uptake. Physiological root characteristics that significantly contribute to the plant ability for P and K uptake varied considerably between genotypes, suggesting that P and K absorption properties of corn roots may be under genotypic control (Nielsen and Barber, 1978). Hybrids also differ in their response to different levels of nutrient availability, whether due to inherent soil fertility level or through fertilization management strategies. The genotype-specific response to different fertility levels of N, P and K in tissue analysis, grain yield and corn development has been previously documented (Peaslee, 1977; Rehm, 1995; Randall et al., 1997). Seasonal precipitation patterns could also significantly alter corn grain yield response to nutrient vertical stratification and placement (Singh, 1966; Moschler and Martens, 1975; Barber, 1971). This effect would be the consequence of reduced soil

31 8 moisture content negatively affecting root growth and P and K uptake (Olsen et al., 1961; Mackay and Barber, 1985; Mackay and Barber, 1985). In Iowa studies related to K fertilizer placement, Bordoli and Mallarino (1998) unexpectedly found that deep banding of K fertilizer increased corn grain yields even in soils that tested between optimum and very high for this nutrient. Given the lack of correlation between yield and placement responses to K fertilization in relation with soil-test K and the degree of vertical K stratification, they suggested that these responses were driven by weather conditions, generally represented by dry late springs or early summers. Increased no-till corn yields due to banded K fertilization under early season droughty conditions were also reported in Ohio (Yibirin et al., 1993) and Ontario (Vyn and Janovicek, 2001). However, Vyn et al. (2002), also observed that in a continuous no-till system with adequate soil moisture content broadcast placement of K was as good as the deep banded placement of the same nutrient. Scarce research can be found trying to outline the optimum P and K placement for rain-fed strip-till corn with intensive production practices at high yield levels in a cornsoybean rotation. In addition, little research of this nature has accounted for hybrid and/or weather interactions. Therefore, the objectives of this study were (1) to determine the effects of fall deep and broadcast placement of P and (or) K, alone or in combination, on growth, development and yield of strip-till corn in different climatic situation/years, (2) to determine the residual effects of additional broadcast application of K to the previous soybean crop on subsequent strip-till corn, (3) to determine the existence of genotypic variation of strip-till corn in the response to different placements for P and K and to the residual effect of an application of K on the previous soybean crop, and (4) to

32 9 try to detect the soil, crop or yearly weather characteristics and/or interactions that help to understand and explain corn responses to alternate P and K fertilizer placements.

33 10 Materials & Methods Site description The study was located at the Purdue Agronomy Center for Research and Education (ACRE) located near West Lafayette, Indiana (40 28 N Lat., W Lon.). In 2005, the soil at the experimental site was characterized as a Drummer soil (fine, silty, mesic Typic Haploquoll), nearly level, very deep, poorly drained and with a silty clay loam texture. In 2006, the study moved to a different field at the same research center. The soil at this site was characterized as a Raub-Brenton complex (fine, silty, mesic Aquic Argiudoll). This soil has a 0 to 1 percent slope, and is somewhat poorly drained. It is a deep, silt loam soil. Both fields have systematic subsurface tile drainage. Field history The field used in 2005 has been in a strip-till corn / no-till soybean rotation since 2003, following the same experiment layout and treatment randomization. The only exception is that those plots representing deep-banded application of P alone and K alone were interchanged between 2003 and 2005; consequently Banded P and Banded K treatments in 2003 became the Banded K and Banded P treatments, respectively, in The intent of the decision to alternate Banded P alone and Banded K alone treatments was to maintain a more balanced P/K nutritional status in these plots since they were initially at medium concentrations for both P and K. The field used in 2006, which actually consists of two adjacent fields of equal size, has been in a strip-till corn / no-till soybean rotation with the same identical