Manipulating Planting Density and Nitrogen Fertilizer Application to Improve Yield and Reduce Environmental Impact in Chinese Maize Production

Abstract

Relatively low nitrogen (N) efficiency and heavy environmental costs caused by excessive N fertilizer applications with outdated fertilization techniques are current cultivation production problems with maize among smallholders in North China Plain. Although many studies have examined agronomical strategies for improving yields and N use, the integrated effects of these measures and the associated environmental costs are not well understood. We conducted a 2-year field study with two densities (67,500 plants ha-1, which was similar to local farmers’ practices, and 90,000 plants ha-1) and three N rates (0, 180, and 360 kg ha-1, the rate local farmers’ commonly apply) to test the integrated effects for maize production at Wuqiao experimental station in North China Plain. The higher planting density produced significant increases in grain yield (GY), N use efficiency (NUE), agronomic N efficiency (AEN), and N partial productivity (PFPN) by 6.6, 3.9, 24.7, and 8.8%, respectively; in addition, N2O emission and greenhouse gas intensity decreased by 7.3 and 4.3%, respectively. With a lower N application rate, from 360 to 180 kg ha-1, GY was unchanged, and NUE, AEN, and PFPN all significantly increased by 6.2, 96.0, and 98.7%, respectively; in addition, N2O emission and greenhouse gas intensity decreased by 61.5 and 46.2%, respectively. The optimized N rate (180 kg N ha-1) for the 90,000 plants ha-1 treatment achieved the highest yield with only 50% of the N fertilizer input commonly employed by local farmers’ (360 kg N ha-1), which contributed to the increased N-uptake and N-transfer capacity. Therefore, our study demonstrated that agronomical methods such as increasing planting density with reasonable N application could be useful to obtain higher GY along with efficient N management to help lower environmental costs of maize production.

Agronomic Responses of Maize Hybrids to Row Spacing and Plant Population in the Summer and Winter Seasons in Brazil

“…However, most other yield components are defined at a later stage in plant development, that is, the ear size and grain size are determined by the V12 and R2‐R3 stage, respectively, and therefore they could be affected by environmental factors, such as intraspecific competition caused by a higher number of plants per area. Our results are in agreement with most recent studies that have shown a linear decrease in the number of ears per plant, kernel length and weight, and ear length in response to an increase in plant population in maize (Xu et al, 2017a; Milander et al, 2016; Qian et al, 2016; Testa et al, 2016; Haegele et al, 2014; Hernández et al, 2014; Van Roekel and Coulter, 2012; Kappes et al, 2011). However, we found no plant population effect for the kernel weight in the winter season.…”

“…Irrespective of the environmental factors, maize GY response to increasing plant population often follows a quadratic model (Assefa et al, 2018; Li et al, 2018; Leolato et al, 2017; Qian et al, 2016; Trachsel et al, 2015; Novacek et al, 2013; Van Roekel and Coulter, 2012; Kappes et al, 2011; Demétrio et al, 2008; Sarlangue et al, 2007; Sangoi et al, 2002). However, environmental factors, for example, climatic conditions and technical management, have significantly influenced optimum plant population for GY in maize (Xu et al, 2017a, Nelson et al, 2015; Hernández et al, 2014; Hammer et al, 2009; Sangoi et al, 2002). In our study, the GY presented a quadratic response to increasing plant population in both summer and winter seasons, and the optimum plant population (the number of plants that maximized GY) was 78,688 (12,167 kg ha −1 ) in the summer season, and 71,206 plants ha −1 (6135 kg ha −1 ) in the winter season.…”

Doses and splitting of nitrogen in two sowing densities of the flint yellow maize hybrid

“…En ese contexto, la cantidad de N y su fraccionamiento y la interacción con la densidad poblacional, son considerados por diversos autores como factores muy importantes para alcanzar altos rendimientos en el maíz (Sallah et al, 2009;Melo et al, 2011;Ciampitti et al, 2013;Lana et al, 2014;Mahdi y Ismail, 2015;Trachsel et al, 2016;Xu et al, 2017). En ese sentido, es necesario realizar más estudios evaluando dichos factores, en razón de haber carencia de informaciones para las condiciones de la costa peruana.…”

Optimal Wheat Seeding Rate is Influenced by Cultivar‐Specific Topsoil and Subsoil Root Traits

“…G rain yields can be increased with many agricultural management practices, including planting crops at optimal seeding rate (Lloveras et al, 2004; Xu et al, 2017). In general, grain yield increases as planting density increases to a certain level (Arduini et al, 2006), after which it decreases, mainly due to resource limitation and strong competition between plants (Paynter and Hills, 2009; Xu et al, 2017). In semiarid areas, drought is the greatest environmental stress affecting crop yields (Ehdaie et al, 2008; Palta and Yang, 2014; Song et al, 2009).…”

“…However, lack of straightforward and efficient methods for studying root systems has hindered the research on the relationship between root traits and optimal seeding rate (Den Herder et al, 2010; Gewin, 2010). Thus, it is essential to understand the interaction between seeding rate and root traits so as to select high‐yielding genotypes that tolerate high planting densities which could reach maximum yield in semiarid regions (Tollenaar and Lee, 2002; Xu et al, 2017).…”