Mitigation options for N₂O emission from a corn field in Kalimantan, Indonesia

Figures & data

Table 1 Soil properties of the plough layer of the soils used

Properties	Value
Sand (%)	66.4
Loam (%)	24.0
Clay (%)	9.6
Organic C (g kg^−1)	19.7
Total N (g kg^−1)	1.3
Total P (mg kg^−1)	11.5
Total K (mg kg^−1)	9.6
pH	4.6
Cation exchange capacity (c(+)mol kg^−1)	29.7
NH^+ 4 (mg kg^−1)	0.02
NO^− 3 (mg kg^−1)	0.04
Viable bacteria (×10^6 c.f.u. g^−1)	2.2
Viable fungi (×10^5 c.f.u. g^−1)	3.0
Ammonium oxidizer (×10^2 MPN g^−1)	1.4
Nitrite oxidizer (×10^2 MPN g^−1)	1.4
MPN, most probable number.

Table 2 Nitrous oxide emission, number of ear of stem, grain yield and above-ground biomass as affected by fertilizer type in South Kalimantan

Treatment	N2O emission (mg N m^−2 crop season^−1)	Number of ear of stem (no. ha^−1)	Grain yield (ton ha^−1)	Above-ground biomass (ton ha^−1)
Control	21.2^c (20.4)	62,220^a (10,184)	5.02^a (1.14)	10.13^b (1.78)
Urea	691.7^a (109.7)	82,220^a (16,778)	6.30^a (1.83)	15.12^b (2.28)
Urea + DCD	21.1^c (9.0)	77,780^a (26,243)	5.64^a (1.79)	21.43^ab (1.82)
LP-30	57.3^b (53.5)	66,620^a (37,119)	6.33^a (3.84)	25.28^a (3.96)
Means followed by the same letters are not significantly different at P < 0.05. Values in parentheses indicate standard deviation. DCD, dicyandiamide; LP-30, controlled-release fertilizer.

Figure 1  Nitrous oxide (N2O) emissions as affected by fertilizer application in a corn field in South Kalimantan. Error bars are standard deviation of the mean. DCD, dicyandiamide; LP-30, controlled-release fertilizer.

Figure 2  Inorganic N contents of soil-pore water in South Kalimantan. Different lowercase letters indicate significant differences in nitrate concentrations among the treatments at P < 0.05. Different capital letters indicate significant differences in ammonium concentrations among the treatments at P < 0.05. Error bars are standard deviation of the mean. DCD, dicyandiamide; LP-30, controlled-release fertilizer.

Figure 3  Inorganic soil N contents in South Kalimantan. Different lowercase letters indicate significant differences in nitrate concentrations among the treatments at P < 0.05. Different capital letters indicate significant differences in ammonium concentrations among the treatments at P < 0.05. Error bars are standard deviation of the mean. DCD, dicyandiamide; LP-30, controlled-release fertilizer.

Table 3 Nitrous oxide emission indices

Treatment	Gram N2O per 1,000 ear of stem	Gram N2O per ton grain yield	Gram N2O per ton plant biomass
Control	3.8^b (3.7)	47.6^b (44.0)	22.5^b (21.0)
Urea	88.3^a (31.2)	1,158.3^a (386.3)	473.0^a (153.3)
Urea + DCD	3.0^b (2.0)	44.2^b (32.6)	10.0^b (4.4)
LP-30	15.6^b (16.8)	163.6^b (197.2)	25.3^b (25.5)
Means followed by the same letters are not significantly different at P < 0.05. Values in parentheses indicate standard deviation. DCD, dicyandiamide; LP-30, controlled-release fertilizer.