Urease Inhibitor and Irrigation Management to Mitigate Ammonia Volatilization from Urea in No-Till Corn

Abstract

High nitrogen (N) losses by ammonia (NH 3 ) volatilization from urea can compromise nitrogen fertilization efficiency and corn yield. The purpose of this study was to assess the effects of irrigation management and the addition of the urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT) on NH 3 -N losses from urea and on corn yield. To this end, two experiments were carried out in the 2011/12 crop season on a sandy clay loam Acrisol in the Central Basin region of Rio Grande do Sul, southern Brazil. Experiment I consisted of two different N sources (urea and urea plus the inhibitor) at a rate of 200 kg ha -1 N and two corn sowing times [viz., an early time (Sept. 3, 2011) and an intermediate time (Oct. 3, 2011)]. Experiment II considered a combination of three irrigation management systems (viz., without irrigation on the fertilization day and on the next 7 days; 20 mm of water immediately before N fertilization; and 20 mm water after N fertilization) and two N sources (urea and urea plus the inhibitor) at 150 kg ha -1 N. A control treatment without topdressed N fertilization was also performed in parallel with the two experiments. The NH 3 -N losses from common urea increased with increasing soil moisture in Experiment I (25 % applied N), and with irrigation before N fertilization in Experiment II (27 % applied N). The inhibitor reduced NH 3 -N losses from urea by 46 to 80 %. Also, irrigation after fertilization reduced ammonia volatilization by 83 % on average, with little effect from the inhibitor. The effects of the inhibitor and post-fertilization irrigation on the mitigation of NH 3 losses by volatilization from urea were not additive; in addition, they led to no increase in corn yield.

Vegetation indices in the prediction of biomass and grain yield of white oat under irrigation levels

“…For instance, in the present study, there was a difference in the values between treatments, since, according to Zhang et al (2011), water stress decreases the chlorophyll content in the leaves, affecting the NDVI readings. This is because the treatments with a small water application layer increase N losses by volatilization (Viero et al 2017). In addition, water is the transport medium of nutrients for plants and, therefore, water deficiency in the soil leads to nutritional stress in plants (Lisar et al 2012).…”

Corn Cropping System And Nitrogen Fertilizers Technologies Affect Ammonia Volatilization In Brazilian Tropical Soils

“…Other results on grain yield, N extraction by the grains and straw show that there is reduction of ammonia losses with the use of inhibitors and other technologies for fertilizers, but these losses were not followed by increased N extraction by the grains, straw and yield 31,14,32 , although they did not estimate the potential supply of N by the soil organic matter.…”

“…1). That is because when urea is applied to the soil, without any additive or technology that reduces its solubility or the hydrolysis rate, ammonia is rapidly created in the solution and catalyzed by urease into NH 3 and CO 2 14,10 . If not incorporated, this ammonia becomes susceptible to losses by volatilization.…”

“…The areas under NT system have increased in Brazil due to the NT system advantages, such as increased organic matter content, reduced losses of soil and nutrients by erosion, and increased maintenance of soil moisture 12,13 . On the other side, in NT systems the presence of straw on the soil surface intensi es the N-NH 3 losses, particularly with the application of urea 14 , being 25% greater than the N-NH 3 losses in conventional tillage systems (T system) 3 . The increase in soil organic matter content enhances the activity of urease, enzyme Thus, it is increasingly important to adopt fertilizer technologies that are able to ensure greater N use e ciency towards 4R's stewardship.…”

Ammonia Volatilization from Soil-Applied Organic Fertilizers

“…Advanced studies on ammonia volatilization from synthetic fertilizers such as urea are available. To reduce N losses through volatilization, urea has been applied together with urease inhibitors, with subsequent incorporation of fertilizer into the soil (Viero et al, 2017). However, other technologies such as urea-coating with micronutrients (Stafanato et al, 2013), compaction with sulfur and bentonite (Oliveira et al, 2014), and urea mixtures with more acidic fertilizers such as ammonium sulfate have been studied.…”