Varying the rate of crop production inputs such as fertilizer and seed makes intuitive sense, as farmers have long observed differences in crop yield in various areas of a single field. The availability of spatial yield information from combines equipped with yield monitors has provided a good resource for improved management.
So, optimizing inputs to match yield potential of different areas within fields may increase profit and reduce the environmental impact associated with over-application of fertilizer or pesticides. With recent substantial increases in grain and fertilizer prices, even small changes in management may have the potential to significantly impact profit from a field.
Scientists with the University of Nebraska-Lincoln (UNL) compared an approach to site-specific nitrogen and seed density management for irrigated maize, based on soil properties and yield potential zones, to whole field uniform management based on current University of Nebraska best management practices (BMPs).
The researchers wanted to know if the site-specific approach could increase yield or nitrogen-use efficiency (the amount of grain produced per kilogram of nitrogen applied), and the effect of site-specific management on profitability. The study was conducted on two irrigated maize fields in Nebraska in 2003 and 2004 -- a total of four site-years.
Four treatments were then compared each year in field length strips, evaluating uniform management of nitrogen and seed density (current BMP), variable nitrogen rate plus uniform seed density, uniform nitrogen rate plus variable seed density, or both variable nitrogen rate and seed density. The variable nitrogen rate was based on yield potential within each zone, spatial patterns of soil organic matter within each zone, and zone-average residual soil nitrate-nitrogen values, using the University of Nebraska recommendation algorithm for maize.
Yield levels in both years generally followed the order of historical yield zones, though at Site 1 in 2003 average grain yields were not different among yield zones. Uniform nitrogen and seed density management resulted in high yields for all four site years, and site-specific management strategies resulted in no or small yield increases. Only at Site 1 in 2003 were there small but statistically significant yield increases with variable rate nitrogen management. There were no significant effects of seed density on yield, nor any interactions between seed density and nitrogen rate.
Fertilizer nitrogen use efficiency (NUE) was high in all site-years and well above national averages. NUE was particularly influenced by the amount of residual nitrate-nitrogen present in the soil profile prior to planting. At Site 1, NUE tended to be highest with the strategy that combined variable rate nitrogen with uniform seed density. At Site 2 in 2003, there was no advantage to variable rate nitrogen in NUE, while in 2004 a variable rate strategy which applied more nitrogen in high-yielding areas of the field resulted in the highest NUE.
At Site 1 in 2003, variable rate nitrogen management increased the gross economic return above fertilizer costs. However, for the other three site-years, there were no significant effects of site-specific management on profitability.
The conclusion of the study was that, using the strategies the researchers selected, they could not demonstrate consistent significant economic benefits to site-specific management. One site-year did indicate an economic benefit to site-specific management, but this was before costs associated with collecting and analyzing site-specific information were included. However, this economic analysis was conducted using 2004 values of grain and fertilizer.
With significant increases in the price of fertilizer and the value of grain in 2007 and 2008, the value of using site-specific management is likely to have increased for those locations where site-specific management has a significant impact on yield, NUE, or both.
The researchers believe variable rate nitrogen application will be most profitable in situations with relatively wide maize to nitrogen fertilizer price ratios, and where a significant yield increase over uniform management is likely. They found little benefit to variable seed density, likely due to plasticity in yield components in response to different plant populations. Site-specific adjustment of seed density in irrigated environments is probably best applied to areas of known low yield potential in order to reduce seed cost.
A peer-reviewed international journal of agriculture and natural resource sciences, Agronomy Journal is published six times a year by the American Society of Agronomy, with articles relating to original research in soil science, crop science, agroclimatology and agronomic modeling, production agriculture, and software. For more information visit: http://agron.scijournals.org.
The American Society of Agronomy (ASA) www.agronomy.org, is a scientific society helping its 8,000+ members advance the disciplines and practices of agronomy by supporting professional growth and science policy initiatives, and by providing quality, research-based publications and a variety of member services.
New insight into why Pierce's disease is so deadly to grapevines
11.06.2018 | University of California - Davis
Where are Europe’s last primary forests?
29.05.2018 | Humboldt-Universität zu Berlin
In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.
Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...
Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
22.06.2018 | Materials Sciences
22.06.2018 | Earth Sciences
22.06.2018 | Life Sciences