Decreasing input–output balance by reducing chemical fertilizer input without yield loss in intensive cropping system in the Coastal Area of southeast Lake Dianchi, Yunnan Province, China

Figures & data

Figure 1. Locations of vegetable fields where the soils for pot experiment were taken from.

Table 1. Descriptive statistics of cultivation in vinyl house fields and properties of soils used for pot experiment.

Variable	Unite	Field 1	Field 2	Field 3	Field 4	Field 5	Field 6
Years of vinyl house cultivation	year	0	0 (1 crop)	5	8	8	3
Cropping intensities of vegetable per year	crop year^−1	−	−	4	5	7	7
Input of chemical fertilizer per year
N	g m^−2 y^−1	29.85	17.00	74.79	142.21	262.49	107.62
P	g m^−2 y^−1	5.61	7.48	16.15	28.05	51.05	18.99
K	g m^−2 y^−1	10.58	14.11	10.26	52.91	96.30	94.99
Input of manure per year
N	g m^−2 y^−1	.00	.00	10.67	85.50	164.99	33.54
P	g m^−2 y^−1	.00	.00	4.25	22.50	75.00	9.66
K	g m^−2 y^−1	.00	.00	7.46	51.75	87.00	20.88
Input−output balance (chemical fertilizer + manure)
N	g m^−2 y^−1	18.77	1.33	33.15	113.88	332.50	53.61
P	g m^−2 y^−1	1.83	5.43	12.51	31.25	112.03	14.62
K	g m^−2 y^−1	−1.59	3.08	-39.05	1.22	91.98	20.05
Properties of soils used for pot experiment
Total N	g kg^−1	2.52	3.06	1.19	2.11	1.52	2.61
Total C	g kg^−1	25.46	27.76	8.15	16.16	12.03	24.40
Nitrate	mg kg^−1	60.20	185.80	288.70	94.20	121.50	274.10
Water-soluble P	mg kg^−1	3.06	18.76	29.40	18.80	21.64	15.30
Water-soluble K	mg kg^−1	94.40	122.00	112.40	89.10	51.40	145.80
EC	ms m^−1	130.90	154.20	69.20	98.90	39.80	57.40
pH		7.41	7.48	7.45	7.11	7.41	7.34

Note: Content in brackets means only one crop of vegetable had been cultivated before soil collecting for pot experiment. Input of chemical fertilizer per year, input of manure per year, and input−output balance in field one indicate cultivation of paddy rice, and those in other fields indicate cultivation of vegetable.

Table 2. Different application amounts of N, P, and K chemical fertilizer.

Treatment	Amounts of N, P, and K (N-P-K mg pot^−1)
Control (N100-P100-K100)	879-386-727
Half-N (N50-P100-K100)	440-386-727
No-N (N0-P100-K100)	0-386-727
Half-P (N100-P50-K100)	879-193-727
No-P (N100-P0-K100)	879-0-727
Half-K (N100-P100-K50)	879-386-364
No-K (N100-P100-K0)	879-386-0

Note: Urea (N ≥ 46.4%), calcium superphosphate (P₂O₅ ≥ 16.0%), and potassium chloride (K₂O ≥ 60.0%) were applied as N, P, and K fertilizer, respectively.

Table 3. Dry matter productions of stem lettuce under different applications of chemical fertilizer.

Treatment	Dry matter production (g pot^−1)
	Soil 1	Soil 2	Soil 3	Soil 4	Soil 5	Soil 6
N100-P100-K100	27.0^a	15.6^a	22.9^a	36.4^a	22.3^a	16.9^a
N50-P100-K100	21.9^ab	19.2^a	31.3^a	41.5^a	19.2^a	13.4^a
N0-P100-K100	13.5^b	18.5^a	29.8^a	21.5^b	12.1^b	15.7^a
N100-P100-K100	27.0^a	15.6^a	22.9^a	36.4^a	22.3^a	16.9^a
N100-P50-K100	19.9^a	19.4^a	19.3^a	34.0^a	20.6^a	15.5^a
N100-P0-K100	4.4^b	11.3^a	29.5^a	37.7^a	18.4^a	19.6^a
N100-P100-K100	27.0^a	15.6^a	22.9^a	36.4^a	22.3^a	16.9^a
N100-P100-K50	19.5^a	20.4^a	25.9^a	32.1^a	17.9^ab	13.2^a
N100-P100-K0	17.5^a	18.2^a	22.2^a	32.8^a	15.1^b	19.4^a

Note: Soils 1–6 mean the soils took from the fields 1–6, respectively. Different letters within a column indicate significant differences (P < .05) by LSD significant difference test.

Table 4. N, P, and K outputs under different application of chemical fertilizer.

Treatment	Output by vegetable (mg pot^−1)
	Soil 1	Soil 2	Soil 3	Soil 4	Soil 5	Soil 6
	N
N100-P100-K100	402.3^a	427.5^a	666.5^a	732.0^a	506.5^a	778.1^a
N50-P100-K100	299.0^ab	524.6^a	767.0^a	559.4^ab	476.0^a	595.8^a
N0-P100-K100	172.1^b	478.3^a	776.0^a	268.2^b	299.0^b	523.9^a
	P
N100-P100-K100	161.6^a	151.1^a	215.8^a	291.8^a	223.7^a	165.2^a
N100-P50-K100	115.6^b	161.2^a	169.7^a	281.0^a	227.2^a	156.1^a
N100-P0-K100	29.3^c	99.6^a	254.1^a	303.4^a	186.0^a	147.6^a
	K
N100-P100-K100	1075.1^a	733.1^a	1015.8^a	927.9^a	1035.3^a	1335.4^a
N100-P100-K50	835.1^b	768.6^a	950.3^a	951.8^a	916.6^ab	875.3^a
N100-P100-K0	588.8^c	622.4^a	710.6^a	738.4^a	705.6^b	999.3^a

Note: Soils 1–6 mean the soils took from the fields 1–6, respectively. Different letters within a column indicate significant differences (P < .05) by LSD test.

Table 5. N, P, and K balances under different application of chemical fertilizer.

Treatment	Balance (mg pot^−1)
	Soil 1	Soil 2	Soil 3	Soil 4	Soil 5	Soil 6
	N
N100-P100-K100	476.7^a	451.5^a	212.5^a	147.0^a	372.5^a	100.9^a
N50-P100-K100	141.0^b	–84.6^b	–327.0^b	–119.4^ab	–36.0^b	–155.8^a
N0-P100-K100	–172.1^c	–478.3^b	–776.0^c	–268.2^b	–299.0^c	–523.9^b
	P
N100-P100-K100	224.4^a	234.9^a	170.2^a	94.2^a	162.3^a	220.8^a
N100-P50-K100	77.4^b	31.8^b	23.3^a	–88.0^b	–34.2^b	36.9^b
N100-P0-K100	–29.3^c	–99.6^b	–254.1^b	–303.4^c	–186.0^c	–147.6^c
	K
N100-P100-K100	–348.1^a	–6.1^a	–288.8^a	–200.9^a	–308.3^a	–608.4^a
N100-P100-K50	–471.1^ab	–404.6^b	–586.3^a	–587.8^b	–552.6^ab	–511.3^a
N100-P100-K0	–588.8^b	–622.4^b	–710.6^a	–738.4^b	–705.6^b	–999.3^a

Note: Soils 1–6 mean the soils took from the fields 1–6, respectively. Different letters within a column indicate significant differences (P < .05) by LSD difference test.

Figure 2. Relationships between soil Nitrate, P, and K and N, P, and K absorbed from sources other than chemical fertilizer by stem lettuce. Numbers on the left of dots represent the numbers of the soils for pot experiment. Note. **significant at P < .01; ns, not significant.

Figure 3. Relationships between N, P, and K absorbed from sources other than chemical fertilizer and N, P, and K recovery efficiencies of chemical fertilizer. Numbers on the left of dots represent the numbers of the soils for pot experiment. Note. *significant at P < .05; ns, not significant.

Figure 4. Relationships between N, P, and K absorbed from sources other than chemical fertilizer and responses of dry matter production to N, P, and K absorbed from chemical fertilizer. Numbers on the left of dots represent the numbers of the soils for pot experiment. Note. **significant at P < .01; ns, not significant.

Table 6. Percentage reduction of N, P, and K inputs without yield loss.

	Soil 1	Soil 2	Soil 3	Soil 4	Soil 5	Soil 6
N	50	100	100	50	50	100
P	50	100	100	100	100	100
K	100	100	100	100	50	100

Notes: Soils 1 to 6 mean the soils took from the fields 1–6, respectively. The effect of reduced N, P, and K was investigated separately.