Effect of conservation tillage on seedling emergence and crop growth-evidences from UAV observations

Figures & data

Figure 1. The geophysical location and experiment field of our study area. The polygons with black outlines are two transects for super high-resolution UAV observations. A. Straw mulching ridge tillage (SMRT), B. Straw mulching strip-till+no-till (SMSTNT), C. Straw mulching wide-narrow row strip-till (SMWRST), D. Straw returning mulch tillage (SRMT), E. Straw mulching wide-narrow row no-till (SMWRNT), F. Straw mulching-deep plowing returning to the field in turn (SMPR) respectively.

Figure 2. Six tillage experiments and associated photographs in 2022 (The photographs were taken on 27 May 2022).

Table 1. The detailed information for six tillage experiments

ID	Tillage Name	Plant spacing	Ridge number	Planting date
1	Straw mulching ridge tillage (SMRT)	25cm	44	3 May
2	Straw mulching strip-till+no-till (SMSTNT)	22cm	40	2 May
3	Straw mulching wide-narrow row strip-till (SMWRST)	25cm	144	5 May
4	Sraw returning mulch tillage (SRMT)	25cm	86	3 May
5	Straw mulching wide-narrow row no-till (SMWRNT)	25cm	38	13 May
6	Straw mulching-deep plowing returning to the field in turn (SMPR)	25cm	238	2 May

Table 2. The detailed band information for DJ Phantom 4-multispectral

Band ID	Band name	Wavelength	Resolution at 15m	Resolution at 100 m
1	Blue	450 ± 16 nm	7.9 mm	5.29 cm
2	Green	560 ± 16 nm	7.9 mm	5.29 cm
3	Red	650 ± 16 nm	7.9 mm	5.29 cm
4	Red edge	730 ± 16 nm	7.9 mm	5.29 cm
5	Near-infrared	840 ± 26 nm	7.9 mm	5.29 cm
6	RGB	/	7.9 mm	5.29 cm

Figure 3. The frame diagram of this study.

Figure 4. Spatial distribution of maize residues pattern across the experiment field. A-F represent the six tillage experiments including SMRT, SMSTNT, SMWRST, SRMT, SMWRNT, and SMPR respectively.

Figure 5. Maize plants are counted by the precision agriculture toolkit at different growth stages.

Table 3. The identified accuracy obtained from quadrats statistical results

ID	Tillage Name	27 May		7 June		17 June
		Detected counts	Actual counts	Detected counts	Actual counts	Detected counts	Actual counts
1	Straw mulching ridge tillage (SMRT)	7	8	8	8	6	8
2	Straw mulching strip-till+no-till (SMSTNT)	7	9	9	9	7	9
3	Straw mulching wide-narrow row strip-till (SMWRST)	8	9	9	9	8	9
4	Straw returning mulch tillage (SRMT)	8	8	8	8	7	8
5	Straw mulching wide-narrow row no-till (SMWRNT)	1	8	7	8	4	8
6	Straw mulching-deep plowing returning to the field in turn (SMPR)	9	9	9	9	5	9

Figure 6. Emergence rate and corresponding straw cover percentages for treatments A-F.

Table 4. The crop diameter and uniformity for different tillages

ID	Tillage Name	Plant diameter
		Mean (m)	STD (m)	CV (%)
1	Straw mulching ridge tillage (SMRT)	0.117	0.014	11.8
2	Straw mulching strip-till+no-till (SMSTNT)	0.115	0.008	7.0
3	Straw mulching wide-narrow row strip-till (SMWRST)	0.115	0.010	8.6
4	Sraw returning mulch tillage (SRMT)	0.119	0.019	16.1
5	Straw mulching wide-narrow row no-till (SMWRNT)	0.115	0.003	2.9
6	Straw mulching-deep plowing returning to the field in turn (SMPR)	0.123	0.025	20.4

Figure 7. Mean and standard deviations in NDVI (a, b) and plant height (c, d) for each treatment during the growing season. A-F represent the six tillage experiments including SMRT, SMSTNT, SMWRST, SRMT, SMWRNT, and SMPR respectively. When calculating the mean and std values, the values of waterlogging areas was masked with the threshold of NDVI_mean-0.5NDVI_std in 24 August.

Figure 8. The spatial distribution and zonal statistics of simulated yield across six tillage treatment. When calculating the zonal mean and std values, the values of waterlogging areas was masked with the threshold of NDVI_mean-0.5NDVI_std in 24 August.

Figure 9. The waterlogging observed from UAV visible images (27 July, a), NDVI (27 July, b), and DSM images (27 May) for our experimental field.