Retaining soil water in farming systems using strip & disc machinery 2024

This project has enabled one demonstration site to be conducted in 2024 in a low rainfall farming system at Buckleboo to enable extension of past EP demonstration site results and results from other regions, and to further investigate:

What are the measurable differences in stripper stubble vs conventional draper stubble sown using a disc seeding system in lentils? (e.g. plant growth, increased stored soil water in-season, weeds, pests, disease, yield, soil cover, nutrition).

Demonstration site information, prepared by Buddhi Chaudhary, SARDI Minnipa Agricultural Centre:

Site selection was undertaken on 1 May 2024 and soil sampling for soil water was taken after sowing on 20 May 2024. The previous 2023 trial site was sown and rolled by the grower prior to this project being funded, so a new trial site was selected and implemented for 2024 to demonstrate lentil growth in standing and rolled stripper stubble.

The site was sown by the landholder with Hallmark lentils on 3 May with 55 kg/ha of 15:13:11 (Granulock Z 15 S) fertiliser. Pre-sowing and post sowing pre-emergent (PSPE) herbicides were applied by the grower. Four soil core samples of each depth 0-10 cm, 10-30 cm, 30-60 cm and 60-90 cm were collected and combined into one composite sample to represent each depth for each strip. A subsample of each composite sample had been taken and dried to obtain the average moisture content of each depth (Figure 1). Figure 1 shows there are no differences in soil moisture down the soil profile (as expected) due to the stubble treatments only being implemented on 9 May 2024 when the project was funded.

Figure 1. Average pre-sowing soil moisture content cross the soil profile (0-10 cm, 10-30 cm, 30-60 cm and 60-90 cm) from the high stubble and rolled stubble treatment plots implemented at Buckleboo 2024.

Stubble dry matter cut was conducted by measuring two 0.5m2 quadrat cuts in plots for soil cover assessment. The results of the average dry weight of the standing stubble (2.21 t/ha) was not significantly different to the rolled stubble treatments (1.58 t/ha).

Figure 2. Average stubble weight (t/ha) from both high and low stubble treatments at the Buckleboo site 2024.

Plant establishment assessments were conducted on the 4 July 2024, when most of the lentils were at 2-3 node stage (Figure 3). The plant establishment count results did not show a significant difference in plant density with an average of 77.2 plants/m2 in high stubble strips and 77 plants/m2 in rolled stubble strips (Figure 4).

Figure 3. Lentils establishments in high stubble (left) and rolled stubble (right) treatment strips at Buckleboo 2024. Figure 4. The average density of established plants in both high and rolled stubble treatments at Buckleboo 2024.

Early-stage plant biomass (lentil dry matter) measurements were conducted on 17 July 2024 by harvesting 50 cm rows of sticks on both sides at two areas in the plot. The harvested sample was oven dried at 70°C for 48 hours for the dry matter measurements (Figure 5). There were no differences in early lentil biomass (0.17t/ha) due to the stubble treatments implemented.

Yield results to be added as they are processed and analysed.