18th Congress of the European Society for Agronomy

Unveiling the short-term impacts of conservation agriculture: a two-year experiment in the Tuscany region, Italy

Aug 30, 2024, 11:20 AM

15m

Les Horizons (2nd floor) (The Couvent des Jacobins)

Oral Synergies of technologies Future & optimization

Speaker

Marco Napoli (Department of Agriculture, Food, Environment and Forestry (DAGRI) - University of Florence)

Description

1. Introduction: In the Mediterranean context, conservation agriculture (CA) is gaining importance due to the rising costs of conventional agriculture (CN) (Cicek et al., 2023). Various solutions have been identified to mitigate the initial drawbacks of switching from CN to CA, but yield losses and soil compaction still occur. The aim of the experiment was to assess the short-term effects of switching from CN to CA. In particular, the effect of switching from conventional (CT) to reduced tillage (RT) with and without cover crop (CC) management was evaluated.
2. Materials and methods: The study was performed from October 2021 to February 2024 (2 growing seasons; GSs) at the Tereto Living Lab of the Tuscany region (Arezzo, Italy). The soil is characterized by a clay-loam texture (sand 23%, Silt 42%, and clay 35%), an alkaline pH (8.2), an initial bulk density of 1.32 t m-3, and a low content of organic matter (1.73%). The climate of the area is Mediterranean, with an average year temperature of 14°C and average annual rainfall of 742 mm. Before the start of the experiment, a two-crop rotation of a winter and a spring crop was applied for more than 5 years with conventional ploughing, leaving fallow for several months. After the start of the experiment, only chisel plough was passed over the RT plots. The experimental design was a completely randomized block design (3 blocks and 3 replications per block) with tillage as the main factor, and CC nested into tillage as split plot. A crop rotation of winter and spring cereals (winter wheat and spring barley, respectively) was applied. Tillage radish (TR; Raphanus sativus L. var. longipinnatus) was selected as CC between the two main crops compared to fallow management. The biomass and grain yield (GY) of the different crops were determined at maturity. Undisturbed soil samples were collected for bulk density (BD) measurement at the following soil depths: 0-5, 5-10, 10-20, and 20-30 cm.
3. Results: At the beginning of the trial, the average BD was about 1.34 (0.01) t m-3. BD values measured in RT after the 1st GS significantly increased at 0-5, 5-10, 10-20, and 20-30 cm by 3.84%, 7.33%, 4.11%, and 4.36%, respectively, while BD increased in CT by 1.94%, 1.01%, 0.15%, and 1.19%, respectively, compared to the initial values. With respect to the initial values, the average BD measured after the 2nd GS at 0-5, 5-10, 10-20, and 20-30 cm, increased by about 3.54%, 7.33%, 4.04%, and 4.36%, respectively in RT, while it increased by about 3.43%, 6.20%, 7.57%, and 4.33%, respectively, in CT.
   GY of winter wheat measured in TR was significantly lower than that measured in CT by about 21%, likewise, GY of spring barley in RT was significantly lower by 41% compared to that measured in CT. Furthermore, the CC biomass in RT measured in the 1st and 2nd GS was significantly lower by 69% and 73%, respectively, compared to that in CT. The GY of spring barley grown after the TR treatment was significantly higher by 21% in RT and by 11% in CT compared to that grown after fallow.
4. Discussion: The study confirms the initial disadvantages of switching from CN to CA, as the effect of RT on soil physical properties was detected just after the TR termination. RT determined a significant increase in BD, which negatively affected crop yield. Moreover, the integration of different CN practices led to a reduction in the yield gap. In particular, the sowing of TR in RT was effective in reducing the yield loss of spring barley. Similar results were reported by Landschoot et al.(2019), as they detected a mitigation of yield losses in a RT system by CC sowing. On the other hand, the beneficial effect of TR was limited by the reduction in biomass accumulation in RT with respect to CT.
5. References Cicek, H., et al. 2023. A critical assessment of conservation agriculture among smallholders in the Mediterranean region: adoption pathways inspired by agroecological principles. Agron. Sustain. Dev. 43. https://doi.org/10.1007/S13593-023-00926-4
   Landschoot, S., et al. 2019. Does shifting from conventional to zero tillage in combination with a cover crop offers opportunities for silage maize cultivation in Flanders? J. Plant Nutr. Soil Sci. https://doi.org/10.1002/JPLN.201900160