Canola production and effect on soil chemical properties in response to different residue levels from three biannual crop rotations

Figures & data

Figure 1. Canola plot for the biannual rotation experiment

Table 1. Soil chemical properties at the 0–0.2 m depth before study initiation (2015–2016 season) and before different residue incorporation levels of wheat, durum wheat, and corn crops (2018–2019 season)

Parameters	Start of the experiment (2015)	Before residue incorporation of the three crops (2018)
		Bread wheat	Durum wheat	Corn
Clay (%)	16.7	nd	nd	nd
Silt (%)	44.6	nd	nd	nd
Sand (%)	38.7	nd	nd	nd
Bulk density (g cm^−3)	1.00	nd	nd	nd
pH (soil:water 1:2.5)	5.52	6.19	6.25	6.13
Organic matter (g kg^−1)	109.2	85.0	82.3	88.5
EC (dS m^−1)	0.11	nd	nd	nd
Available N (mg kg^−1)	54.1	6.5	6.2	6.4
Olsen P (mg kg^−1)	21.3	19.3	17.9	17.5
Exchangeable K (cmolc kg^−1)	0.54	0.55	0.54	0.46
Exchangeable Ca (cmolc kg^−1)	4.20	6.56	6.67	5.16
Exchangeable Mg (cmolc kg^−1)	0.36	0.38	0.43	0.41
Exchangeable Na (cmolc kg^−1)	0.08	0.05	0.05	0.04
Exchangeable Al (cmolc kg^−1)	0.12	0.05	0.04	0.06
Available S (mg kg^−1)	23.5	55.2	48.6	59.7

EC: electrical conductivity; nd: not determined.

Table 2. Significance testing of canola grain yield, residue and dry matter production, harvest index, and soil chemical properties after the canola crop harvest as affected by three previous crops and incorporation of four residue levels

Parameter	Trait	Previous crop (C)	Residue level (R)	C × R interaction
Crop	Yield	NS	NS	NS
	Residue	*	NS	NS
	Dry matter production	*	NS	NS
	Harvest index	*	*	*
Soil chemical properties	pH	NS	NS	NS
	Organic matter	**	*	NS
	Nitrogen concentration	**	NS	NS
	Phosphorous concentration	**	NS	NS
	Calcium concentration	*	NS	NS
	Magnesium concentration	**	NS	NS
	Potassium concentration	**	**	NS
	Sodium concentration	**	NS	**
	Aluminum concentration	NS	NS	NS
	Sulfur concentration	**	NS	*

*Significant at p < 0.05; **Significant at p < 0.01; NS: nonsignificant.

Table 3. Canola grain yield, residue and dry matter production, and harvest index as affected by three previous crops and incorporation of four residue levels

Previous crop	Residue level (%)	Grain yield (Mg ha^−1)	Residue production (Mg ha^−1)	Dry matter production (Mg ha^−1)	Harvest index (%)
Bread wheat	0	4.3 Aa	10.6Ba	14.9Ba	28.8Ab
	50	4.3 Aa	9.5Ba	13.8 Ba	30.9Aa
	100	4.4 Aa	10.3Ba	14.7Ba	29.9Aab
	200	4.3 Aa	10.6Ba	15.0 Ba	28.8Ab
Durum wheat	0	4.0 Aa	9.6 Ba	13.6 Ba	29.6Aa
	50	4.1 Aa	9.6 Ba	13.7 Ba	29.7Aa
	100	4.8 Aa	11.1Ba	15.9 Ba	30.1Aa
	200	4.5 Aa	11.1 Ba	15.6 Ba	29.1Aa
Corn	0	4.5 Aa	11.7Aa	16.2Aa	27.9Bb
	50	4.5 Aa	11.2Aa	15.7Aa	28.5Bab
	100	4.6 Aa	11.1Aa	15.8Aa	29.5Ba
	200	4.6 Aa	11.0Aa	15.6Aa	29.4Ba

Different uppercase letters in the same column indicate differences between previous crops as a mean of the four incorporated residue levels according to Tukey’s test (p < 0.05).

Different lowercase letters in the same column for the same previous crop indicate differences between residue level treatments according to Tukey’s test (p < 0.05).

Table 4. Soil chemical properties after the canola crop harvest as affected by three previous crops and incorporation of four residue levels

				N	P	Ca	Mg	K	Na	Al	S
Previous crop	Residue level (%)	pH	MO %	mg kg^−1		cmol kg^−1					mg kg^−1
Bread wheat	0	6.01Aa	10.2 Ba	11.3ABa	23.4ABa	5.65Aa	0.47Aa	0.50 Ba	0.06Aa	0.05Aa	42.1ABb
	50	6.02Aa	10.5 Ba	11.9ABa	21.9ABa	5.76Aa	0.49Aa	0.56 Ba	0.06Aa	0.04Aa	43.4ABab
	100	6.00Aa	10.6 Ba	8.7ABa	21.8ABa	5.12Aa	0.37Aa	0.56 Ba	0.05Aa	0.04Aa	49.2ABab
	200	6.01Aa	10.6 Ba	11.5ABa	22.0ABa	5.55Aa	0.44Aa	0.74 Ba	0.06Aa	0.04Aa	52.6ABa
Durum wheat	0	5.97Aa	9.7 Ba	9.1 Ba	21.2 Ba	4.75 Ba	0.31 Ba	0.40Cc	0.03Ca	0.04Aa	67.0Aa
	50	6.05Aa	10.3 Ba	8.4Bab	22.6 Ba	4.63 Ba	0.34 Ba	0.43Cbc	0.02Ca	0.03Aa	54.5Aab
	100	6.13Aa	10.3 Ba	7.5 Bab	18.1 Ba	4.63 Ba	0.34 Ba	0.52Cb	0.03Ca	0.03Aa	39.2Ab
	200	6.06Aa	10.3 Ba	6.3Bb	18.0 Ba	4.69 Ba	0.34 Ba	0.61Ca	0.03Ca	0.04Aa	62.7Aab
Corn	0	6.00Aa	10.5Aa	11.3Aa	21.8Aa	5.23Aa	0.36Aa	0.61Aa	0.03Bb	0.04Aa	32.4Ba
	50	6.01Aa	10.7Aa	12.7Aa	22.7Aa	5.06Aa	0.38Aa	0.73Aa	0.04 Bab	0.05Aa	38.9 Ba
	100	5.99Aa	11.3Aa	13.8Aa	26.4Aa	5.48Aa	0.46Aa	0.84Aa	0.04 Bab	0.06Aa	45.5 Ba
	200	6.12Aa	11.7Aa	15.6Aa	24.3Aa	6.09Aa	0.48Aa	0.90Aa	0.07 Ba	0.04Aa	42.8 Ba

Different uppercase letters in the same column indicate differences between previous crops as the mean of the four incorporated residue levels according to Tukey’s test (p < 0.05).

Different lowercase letters in the same column for the same previous crop indicate differences between residue level treatments according to Tukey’s test (p < 0.05).

Table 5. Post-harvest soil chemical properties of the canola crop that showed a correlation greater than 50% and statistical significance for the harvest date

Soil chemical properties		Correlation value (R)	Significance value (p < 0.01**)
pH	Calcium	0.82	**
pH	Magnesium	0.68	**
pH	Aluminum	−0.85	**
pH	Sulfur	−0.70	**
Nitrogen	Magnesium	0.52	**
Nitrogen	Potassium	0.51	**
Nitrogen	Sodium	0.64	**
Phosphorous	Aluminum	0.56	**
Potassium	Calcium	0.57	**
Potassium	Magnesium	0.62	**
Potassium	Sulfur	−0.55	**
Calcium	Magnesium	0.90	**
Calcium	Aluminum	−0.67	**
Calcium	Sulfur	−0.73	**
Magnesium	Sodium	0.60	**
Magnesium	Aluminum	−0.59	**
Magnesium	Sulfur	−0.76	**
Aluminum	Sulfur	0.58	**