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Figure 1.
FTIR spectra of Cf, Hcf-P, Hcf-G and their raw materials. (a) is for the raw material such as Cf, (b) is the intermediate products for Cf-H, Hcf-P and Hcf-G. Cf: urea and potassium chloride mixture served as control, HA: humic acid, GABA: gamma butyric acid, Cf-H: Cf and HA mixture. Hcf-P: Compound fertilizer made of urea, potassium chloride, HA, and PASP. Hcf-G: Compound fertilizer made of urea, potassium chloride, HA, and GABA.
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Figure 2.
SEM images of Cf (a, d); Hcf-P (b, e); and Hcf-P (c, f). (a, b & c) are surface form, (d, e & f) are section shape. The multiple of the scanning electron microscope image is x500. Cf: urea and potassium chloride mixture served as control. Hcf-P: Compound fertilizer made of urea, potassium chloride, HA, and PASP. Hcf-G: Compound fertilizer made of urea, potassium chloride, HA, and GABA.
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Figure 3.
Nitrogen cumulative leaching rate of different fertilizers. Cf: urea and potassium chloride mixture served as control. Hcf-P: Compound fertilizer made of urea, potassium chloride, HA, and PASP. Hcf-G: Compound fertilizer made of urea, potassium chloride, HA, and GABA.
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Figure 4.
Response surface analysis of factors affecting evenness.
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Formulation Moisture
(%)Hygroscopicity
(%)Hardness
(N)Sphericity
(%)Nutrition N (%) K (%) Organic matter (%) Hcf-P 5.4a 3.0a 25.3ab 86.7a 19.2 27.2 16.1 Hcf-G 5.3a 3.2a 27.2a 88.2a 18.9 26.8 16.0 Cf 3.4b 2.3b 21.7b 86.9a 23.2 31.8 / Cf: urea and potassium chloride mixture served as control. Hcf-P: Compound fertilizer made of urea, potassium chloride, HA, and PASP. Hcf-G: Compound fertilizer made of urea, potassium chloride, HA, and GABA. Table 1.
Particle characteristics related indicators
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Fertilizer First-order kinetic
equationSecond-order kinetic
equationElovich Freundlich Qe K1 R2 Qe K2 R2 α β R2 n K3 R2 Hcf-P 0.701 0.221 0.960 0.819 0.324 0.992 1.391 0.850 0.992 3.236 0.269 0.958 Hcf-G 0.647 0.247 0.904 0.743 0.424 0.972 1.391 0.870 0.996 3.520 0.271 0.952 Cf 0.745 0.339 0.960 0.835 0.558 0.995 1.529 0.865 0.959 4.391 0.380 0.904 Cf: urea and potassium chloride mixture served as control. Hcf-P: Compound fertilizer made of urea, potassium chloride, HA, and PASP. Hcf-G: Compound fertilizer made of urea, potassium chloride, HA, and GABA. Table 2.
Dynamic formula for cumulative release of leached nitrogen in fertilizer soil column
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Source Sum of squares df Mean square F-value P-value Significance Model 875.40 9 97.27 26.97 < 0.0001 ** A 49.35 1 49.35 13.69 0.0041 ** B 34.70 1 34.70 9.62 0.0112 * C 18.24 1 18.24 5.06 0.0482 * AB 3.11 1 3.11 0.86 0.3748 AC 64.47 1 64.47 17.88 0.0017 ** BC 0.93 1 0.93 0.26 0.6223 A² 262.05 1 262.05 72.67 < 0.0001 ** B² 259.45 1 259.45 71.94 < 0.0001 ** C² 322.30 1 322.30 89.37 < 0.0001 ** Residual 36.06 10 3.61 Lack of fit 27.66 5 5.53 3.29 0.1084 Pure error 8.40 5 1.68 Cor total 911.46 19 A: particle size (mm), B: centrifugal speed (r/min), C: flux (grain/s). * significant (P < 0.05), ** extermely significant (P < 0.01) Table 3.
Variation Variance Analysis of independent variables
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Deal Dry matter (t ha–1) N accumulation (kg ha–1) Yield (t ha–1) NUE (%) NEB (CNY ha–1) 2020 2021 2020 2021 2020 2021 2020 2021 2020 2021 Hcf-P 15.33b 15.93b 185.11ab 161.01b 9.90a 8.32b 65.73ab 61.00b 9,254.94 5,218.33 Hcf-G 17.24a 19.15a 189.42a 175.80a 10.39a 9.30a 71.71a 81.54a 10,460.21 7,666.66 Cu 14.69b 16.16b 170.58b 151.34b 9.72a 7.73b 45.54b 47.57b 8,860.52 3,781.64 NEB is economic benefit. Cu refers to the application of urea by UAV and artificial potassium fertilizer. Cf: urea and potassium chloride mixture served as control. Hcf-P: Compound fertilizer made of urea, potassium chloride, HA, and PASP. Hcf-G: Compound fertilizer made of urea, potassium chloride, HA, and GABA. Table 4.
Dry matter accumulation, nitrogen accumulation and yield at maturity stage of rice
Figures
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Tables
(4)