Effect of Urea Coated with Polyaspartic Acid on the Yield and Nitrogen Use Efficiency of Sorghum (Sorghum bicolor, (L.) Moench.)

Abstract

Innovative approaches to enhance N fertilization to improve season-long N availability are essential to optimal sorghum (Sorghum bicolor, (L.) Moench.) productivity and N use efficiency. A two-year field experiment was conducted in the 2020 and 2021 summer seasons on the North China Plain to determine the effects of a novel urea coated with polyaspartic acid (PAA) (PN) and a control treatment (CN) on grain sorghum yield and N utilization characteristics at four N application rates (0, 60, 120, and 240 kg ha−1). The results showed that sorghum yield, agronomic traits (including leaf area duration (LAD), crop growth rate (CGR), and dry matter accumulation (DMA)), the accumulation of nitrate N and ammonium N in the 0–60 cm soil layer, stover and grain N content, and total N uptake (NUT) in 2020 and 2021 significantly increased as N application rates increased from 0 to 240 kg ha−1, whereas nitrogen agronomic efficiency (NAE), N uptake efficiency (NUpE), and N utilization efficiency (NUtE) varied inversely with increasing N application rates. Compared to CN, PN demonstrated a significant enhancement in grain sorghum yield, LAD, and CGR, from 3.3% to 7.1%, from 4.8% to 6.1%, and from 5.8% to 6.8%, respectively, at 60 and 120 kg N ha−1. PN improved the N availability (mainly nitrate-N) in the sorghum soft dough and the stover and grain N content at harvest and NUT, NUpE, and NAE accordingly compared with CN at the 60 and 120 kg ha−1 N application rates. In short, our two-year field trials demonstrated that PN with 120 kg N ha−1 is recommended in grain sorghum to optimize sorghum productivity and nitrogen use efficiency at the current yield level in the North China Plain.

Urea Coated with Polyaspartic Acid-Chitosan Increases Foxtail Millet (Setaria italica L. Beauv.) Grain Yield by Improving Nitrogen Metabolism

“…It could chelate a variety of nutrient elements, promote the absorption and utilization of fertilizer, and effectively promote the nitrogen metabolism of crops. Recent research has indicated that PASP combined with urea could increase nitrogen accumulation in the upper part of sorghum, and improve nitrogen use efficiency and grain yield [8]; increase NR activity and promote nitrogen assimilation in maize seedlings [35]; and increase the activities of enzymes of nitrogen metabolism and the content of soluble protein in functional leaves of rice [21]. CTS, the other component of PAC, also has good adsorption and sustained-release effects, which can accelerate life activities of microorganisms in soil, promote soil respiration, improve nutrient availability [9], and the fertilizer absorption efficiency of plants [16].…”

“…Also, PASP has notable properties of low production costs and biodegradation [6]. Because of the advantages above, PASP has been widely applied in agriculture as the absorption promoter of fertilizers, a controlled-release agent, and so on [7,8]. CTS is a derivative of chitin and is considered the second most common polymer in the world after cellulose [9].…”

Urea Enhanced with Polyaspartic Acid of a Higher Molecular Weight Significantly Increased Wheat Yield and Nitrogen Use Efficiency

“…Polyaspartic acid (PASP) has a strong absorption capacity for nutrient ions because of the numerous free carboxyl and amide groups in its molecular chains [6]. Thus, PASP can reduce nutrient loss and increase the soil nutrient content [7,8]. PASP has shown a high capacity to stimulate crop growth and nutrient uptake and strengthen crop stress resistance [9,10].…”

“…Therefore, PASP can be used as a controlled-release agent and absorption promoter in fertilizers [7,11] and has become a widely used bioactive organic synergist for high-efficiency urea in practice.…”

“…Urea enhanced with PASP (PASPU), manufactured through incorporating a small amount of PASP into conventional urea without significantly changing the urea production flowchart, has been gradually industrialized with "Duotai Niaosu" as the trade name for many Chinese fertilizer enterprises [12]. Compared with conventional urea, PASPU application in the production of maize, rice, and other upland plants usually contributes to a higher level of available nutrients in the root-feeding zone and more efficient nutrient utilization [13,14], resulting in a significant increase in nutrient absorption, growth rate, biomass, grain yield and quality, and nutrient use efficiency [7,11,14].…”