2020
Ripping and spading improved pulse crop yields at Lameroo Authors: Michael Moodie Research Team: Chris Davies and Todd McDonald 1 Frontier Farming Systems Funded By: Murraylands and Riverland Landscapes Board Project Title: Improving groundcover options with legume production in sands Peer Review: Tanja Morgan Key Words: Soil amelioration, sandy soils, lentil, chickpea, lupin, faba bean, vetch and field pea
Key Messages ● ● ● ●
Ameliorating sandy soils by spading, deep ripping or combinations of the two resulted in large grain yield benefits to all pulse crops except for lupins. The grain yield of chickpea, field pea and faba beans grown on ameliorated sandy soil was equivalent or more than the yield achieved by lupins grown without spading or ripping. Soil amelioration increased vegetative groundcover for lentil, vetch and field pea, but generally reduced groundcover in lupins due to variable crop establishment. The gross margin of all pulse crops except for lupins increased by more than $400/ha following the amelioration of sandy soils.
Background The Murraylands and Riverland Landscapes Board and Mallee Sustainable Farming have identified that legume crops grown on sandy soils in the SA region are providing sub-optimal levels of both productivity and vegetative ground cover protection. The consequence of this is that the soil condition benefits provided by the legume crop during the growing season are rapidly lost due to subsequent wind erosion on these soils. This leaves the soil vulnerable to ongoing erosion and can lead to reduced productivity and groundcover protection of subsequent crops. This project aims to explore and develop methods and practices that will improve longer term groundcover retention on sandy soils where legumes are grown regularly in the rotation. This included investigating which legume crops are most suitable to be grown on sandy soils and evaluation of management practices landholders could implement to maximise biomass and stubble generation and persistence. In the first year of the project, deep ripping sandy soils prior to sowing increased growth and production of legume crops by 22-63%. In 2020, trials were expanded to include spading as an alternative option to address physical soil constraints to legume growth on Mallee sandy soils.
About the trial The 2020 trial site was located 10 km north west of Lameroo. Within the paddock the site is located on a very sandy soil type (Table 1) with non-wetting characteristics.
Page 2 Table 1. Key soil properties at the site
Analyte pH (CaCl2)
0-10c m 5.8
10-30c m 6.6
30-60cm
60-90cm
90-120cm
7.5
8.1
8.4
Organic Carbon (%)
0.4
KCl Sulfur (mg/kg)
7.0
4.9
4.0
3.0
4.7
Chloride (mg/kg)
7.3
1.7
1.7
2.0
2.7
EC 1:5 (dS/m)
0.1
0.0
0.1
0.1
0.2
Boron (mg/kg)
0.4
0.3
0.6
4.2
8.9
Clay (<2 micron) (%)
0.6
0.6
4.6
16.3
18.6
Sand (>20 micron) (%) Silt (2-20 micron) (%)
99.4
99.3
90.0
80.3
75.4
0.0
0.1
5.3
3.3
6.0
Aus Soil Texture
Sand
Sand
Loamy Sand
Sandy Loam
Sandy Loam
Trials tested the effect of soil amelioration techniques of deep ripping and spading on legume crop growth. Overlayed on these treatments are six different pulse crop options: chickpea, lentil, lupin, vetch, faba bean and field pea. The varieties and sowing details for each of these crops are provided in Table 2. In addition, field pea and vetch crop treatments were repeated with canola sown as a companion crop. The aim of the companion crop treatment is to provide trellising and additional anchorage for the legume crop and residues. Table 2. Establishment (plants m2) for each crop and treatment.
Crop
Variety
Target Plants 35
1000 Seed Weight g 209.8
Seeding Rate (kg/ha) 81
Chickpea
PBA Striker
Lentil
120
34
45
Lupin
PBA Hallmark PBA Jurien
45
123.2
61
Vetch
Timok
50
68.9
39
Faba bean Field Pea
PBA Bendoc
25
596
162
PBA Butler
45
176
87
The site was established on the 17th of May 2020. At sowing, all experimental plots were fertilized with Granulock Z (N-11, P-21.8, K-0, S-4) + Zn (1.0) at a rate of 50 kg/ha. All plots were inoculated with the specific rhizobium for each crop type (N, G or E/F) and pre-emergent herbicides and rates were also adjusted for each crop to minimise the risk of damage these high-risk sandy soils. Fungicides, herbicides, and insecticides were applied to ensure trials were not impacted by disease, weeds, and insect pests. At maturity, each crop was harvested with a small plot harvester and grain yields were recorded.
Results & Discussion Crop establishment was generally adequate for most crop to reach its yield potential Table 3). Windy conditions led to infill of furrows with sand post seeding which resulted in variable and low establishment in lupins and the canola within the companion crop treatments. Although not statistically significant due to high variability, lupin establishment was reduced by half in soil amelioration treatments.
Page 3 Table 3. Establishment (plants m2) for each crop and treatment.
Crop
Nil
Spad e 96
Deep Rip 101
Spade + Deep Rip 100
P Value ns
Lentil Chickpea
11 1 26
24
25
26
ns
Lupin
19
11
10
9
ns
Faba bean
20
21
16
22
ns
Vetch
44
37
36
35
ns
Field Pea
26
27
31
34
ns
Vetch
49
44
34
41
n.s
Vetch + Canola Canola
12
0
12
0
Field Pea + Canola Field Pea
30
29
33
33
Canola
16
0
5
0
0.02
Soil amelioration by spading and deep ripping resulted in large yield increases for all crops except for lupins. The highest yield increases were observed in vetch which yielded three times more than the control and lentils which yielded 2.5 times more than the control. However, these two crops also had the lowest overall productivity. Yield was approximately doubled in chickpea, faba bean and field pea. These three crops were at least or more productive than the lupin control. There was no significant effect of amelioration treatments on lupin yields, although the trend was for a negative effect on grain yield due to the variable emergence. The companion cropping treatment tended to improve grain yield in vetch, however this effect is most likely due to an improvement in soil type in the companion crop trial relative to the monocrop trial. Table 4. Grain yield (kg/ha) for each crop and treatment.
Crop
Nil
Lentil
384
Chickpea Lupin Faba bean Vetch Field Pea
Spad e 1045
Deep Rip 1070
Spade + Deep Rip 1032
114 0 207 3 111 4 367
1861
2170
2497
1286
1539
1203
< 0.0001 < 0.0001 n.s
2231
2203
2740
0.001
1207
1343
1139
0.0003
161 9
2882
3212
3383
0.0030 < 0.0001
Vetch + Canola Vetch Canola Field Pea + Canola Field Pea Canola
114 0 87
2014
2478
2514
14
20
16
P Value
< 0.0001 125 5 454
2925
3087
3584
38
158
22
Page 4 Soil amelioration had a significant positive effect on the level of groundcover provided by lentil, vetch, and field pea (Figure 1). Conversely, groundcover levels were lower in spaded and deep ripped plots in lupins because of the variable lupin establishment in these treatments (Figure 1).
Figure 1. Vegetative groundcover measured in October for each crop x treatment combination.
Implications for commercial practice The grain yield benefits from ameliorating sandy soils resulted in significantly greater pulse crop profitability. The gross margin of all pulse crops except for lupin increased by more than $400/ha because of by spading, deep ripping or combinations of the two (Figure 2). This gross margin does not include the cost of the amelioration which is estimated to cost $100-200/ha with the benefits expected to last several seasons. One feature of the gross margin analysis was that ameliorated field pea and chickpea both provided a more profitable option than the un-ameliorated lupins which would be the traditional pulse crop grown on this soil type.
Figure 2. Pulse crop gross margins for the control and the average of the three ameliorated treatments. The prices used were representative of January 2021 prices: Lupin: $393/t; Lentil: $672/t; Vetch: $600/t; Faba Bean; $370/t; Field Pea: $350/t; Chickpea: $610/t. The gross margin does not include the cost of soil amelioration.
Acknowledgements Murraylands and Riverland Landscapes Board Thank you to the McMahon family at Lameroo for hosting the trial site in 2020.