| dc.contributor |
Crop and Soil Environmental Sciences |
|
| dc.contributor |
Alley, Marcus M. |
|
| dc.contributor |
Evanylo, Gregory K. |
|
| dc.contributor |
Follett, Ronald F. |
|
| dc.contributor |
Phillips, Steven B. |
|
| dc.contributor |
Zelazny, Lucian W. |
|
| dc.creator |
Spargo, John T. |
|
| dc.date |
2014-03-14T20:07:17Z |
|
| dc.date |
2014-03-14T20:07:17Z |
|
| dc.date |
2008-02-01 |
|
| dc.date |
2008-02-10 |
|
| dc.date |
2008-03-04 |
|
| dc.date |
2008-03-04 |
|
| dc.date.accessioned |
2023-02-28T18:21:09Z |
|
| dc.date.available |
2023-02-28T18:21:09Z |
|
| dc.identifier |
etd-02102008-174038 |
|
| dc.identifier |
http://hdl.handle.net/10919/26166 |
|
| dc.identifier |
http://scholar.lib.vt.edu/theses/available/etd-02102008-174038/ |
|
| dc.identifier.uri |
http://localhost:8080/xmlui/handle/CUHPOERS/269681 |
|
| dc.description |
No-till management for agronomic crop production is recognized as an effective practice to regain a portion of soil organic matter lost following decades of cultivation. Increasing soil organic matter sequesters C, conserves organic N and concomitantly improves soil quality.
Objectives of this research were to: i) quantify C sequestration rate and N conservation with duration of continuous no-till; ii) measure C stratification with continuous no-till as an indicator of soil quality; and iii) evaluate the Illinois soil N test (ISNT) for its value to predict fertilizer N needs of corn in Virginia.
Objectives i and ii were achieved by collecting soil samples from 63 production fields in the Virginia Coastal Plain that were managed using continuous no-till from 0 to 14 yrs. No-till management resulted in sequestration of 0.308 ± 0.280 Mg C ha⁻¹ y⁻¹ and conservation of 22.2 ± 21.2 kg N ha⁻¹ yr⁻¹ (0-15 cm). The C stratification ratio (0-2.5 cm: 7.5-15 cm) increased with increasing duration of continuous no-till (0.133 ± 0.056 yr⁻¹) due to the accumulation of organic matter at the soil surface indicating improved soil quality with continuous no-till management.
Objective iii was addressed by conducting 29 on-farm fertilizer N response trials in major corn producing areas of Virginia with the duration of continuous no-till management ranging from 0 to 25 yrs. The ISNT values were significantly related to yield without fertilizer N (r² = 0.57; p<0.001) and relative yield (r² = 0.64; p<0.0001). We also found that the ISNT extracted a relatively consistent percentage of total soil N (16.3 ± 0.73 %) suggesting it is a poor indicator of labile N. Total soil N values did almost as well as the ISNT in predicting yield without fertilizer N (r² = 0.53; p = 0.0002), and equally well predicting relative yield (r² = 0.64; p<0.0001). Results do not suggest the ISNT is useful for measuring mineralizalbe N or improving fertilizer N recommendations in Virginia cropping systems. |
|
| dc.description |
Ph. D. |
|
| dc.format |
application/pdf |
|
| dc.publisher |
Virginia Tech |
|
| dc.relation |
JSpargo.pdf |
|
| dc.rights |
In Copyright |
|
| dc.rights |
http://rightsstatements.org/vocab/InC/1.0/ |
|
| dc.subject |
Nitrogen use efficiency |
|
| dc.subject |
carbon trading |
|
| dc.subject |
nutrient trading |
|
| dc.subject |
soil organic matter |
|
| dc.title |
Continuous No-till Management: Implications for Soil Quality, Carbon Sequestration, and Nitrogen Conservation |
|
| dc.type |
Dissertation |
|