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Effects of sprayer height in center pivot system on growth of summer maize under semi-humid climates

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2021 ASABE Annual International Virtual Meeting  2100367.(doi:10.13031/aim.202100367)
Authors:   Xinrui Fan, Weixia Zhao, Jiusheng Li
Keywords:   Canopy interception; Fertigation; Fertilizer use efficiency; Sprinkler irrigation.

Abstract. The installation height of a sprayer is an important consideration for a center pivot when an increasing crop height would change the application pattern of water and fertilizers. Three sprayer heights with nozzle above the canopy (2.8 m above ground surface), near the top of canopy, and within the canopy (1.5 m above ground surface) were compared from the aspects of soil water content, crop physiological parameters, growth parameters, yield, water use efficiency, and fertilizer use efficiency of summer maize under semi-humid climate. The experiments were conducted at the Experimental Station of the National Center for Efficient Irrigation Engineering and Technology Research in Beijing (39°39′ N and 116°15′ E). During the growth season of summer maize, three fertigation events were applied from jointing to grain formation. The results indicated that nozzle installed within the canopy produced a more uniform distribution of soil water content than the nozzle above canopy and near the canopy. Compared with the nozzle above and at the top of the canopy, the soil water content for the treatment of nozzle within the canopy increased by 0.1%~1.9% and 0.5%~4.3%, and the soil mineral nitrogen increased by 12.7%~28.0% and 10.0%~24.6%, respectively. For all three sprayer heights tested, the fertigation during the 6-leaf (V6) to 12-leaf (V12) stages resulted in a clear increase in the relative chlorophyll content (SPAD), photosystem activity (Fv/Fm), and photochemical efficiency (Fv/F0) although the differences among the three heights were statistically insignificant. Thereafter, the fertigations only resulted in a slight increase in SPAD, Fv/Fm, and Fv/F0. No significant differences in plant height, leaf area index (LAI), yield, water use efficiency, and partial factor productivity from applied N of summer maize for different nozzle installation heights were observed. The yield and N fertilizer bias productivity for nozzle installed within the canopy decreased by 6% compared to nozzle installed near the top of canopy. Our study suggested that rising nozzle above the canopy during reproductive stage of maize benefits the direct absorption of nutrient that were intercepted by canopy during fertigation to maximize yields and fertilizer use efficiency.

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