Managing Global Resources for a Secure Future

2017 Annual Meeting | Oct. 22-25 | Tampa, FL

35-12 Soybean Nitrogen Fixation : The Nitrogen Budget.

See more from this Division: SSSA Division: Soil Fertility and Plant Nutrition
See more from this Session: Ph.D. Oral Competition I

Monday, October 23, 2017: 11:05 AM
Marriott Tampa Waterside, Grand Ballroom D

Silvia Carolina Córdova1, Ranae Dietzel1, Mark A. Licht2, Sotiris V. Archontoulis1 and Michael J. Castellano1, (1)Department of Agronomy, Iowa State University, Ames, IA
(2)Department of Agronomy, Iowa State University, Roland, IA
Abstract:
Cereal-legume crop rotations can benefit production, profitability and environmental performance. One benefit of these cropping systems is that legumes are capable of biological N fixation (BNF). However, BNF provides only a portion of total crop N demand and the remaining N requirement must be met from the soil N pool. The portion of total crop N demand met by BNF is variable across years, cultivars, locations, and management practices. If the amount of BNF does not meet or exceed the amount of N harvested, there is risk that the crop will reduce the soil N stock. There is growing concern that soybean is reducing soil N stocks because BNF is consistently less than the amount of N harvested in soybean grain. The aim of our study is to understand the variability in BNF in different environments (i.e., planting date x site), and years. This study was conducted in two sites located in Central and North West Iowa at two planting dates (May 1st and 25th). We used a 15N isotope dilution method to measure BNF throughout the growing seasons of 2015 and 2016 within different plant parts including above and below-ground tissues. Preliminary results have shown that in both sites and years soybean is a net user of soil N rather than a contributor, resulting in a net negative soil N balance.

See more from this Division: SSSA Division: Soil Fertility and Plant Nutrition
See more from this Session: Ph.D. Oral Competition I