Conservation tillage in temperate rice cropping systems: Crop production and soil fertility

• Published in: Field crops research 2024-03, Vol.308, p.109276, Article 109276
• Main Authors: Vitali, Andrea, Moretti, Barbara, Lerda, Cristina, Said-Pullicino, Daniel, Celi, Luisella, Romani, Marco, Fogliatto, Silvia, Vidotto, Francesco
• Format: Article
• Language: English
• Subjects: Conservation tillage; No tillage; Rice grain yield; Soil carbon stock; Soil compaction; Soil organic matter fractions
• ISSN: 0378-4290; 1872-6852
• DOI: 10.1016/j.fcr.2024.109276

Conventional tillage (i.e. ploughing) that is applied in Italian rice fields ensures high grain yields, but may result in negative effects on physical and chemical fertility of soil. Conservation tillage can be a viable alternative to conventional allowing to reduce the environmental and economic impact of rice cultivation. However, there is limited knowledge on the effects of these alternative tillage systems on rice yield and paddy soil fertility in temperate climates. The aim of this study was to evaluate the effects on yield and soil fertility of conservation tillage in the medium term in temperate rice continuous monoculture system. A six-years monocrop rice experiment (2014–2019) was carried out in North-West Italy, comparing three tillage methods: conventional tillage (ploughing – CT), minimum tillage (MT), and no tillage (NT) combined with three N fertilization rates (N0, N − 120 kg N ha−1 year−1, and N + − 160 kg N ha−1 year−1). The study evaluated yield, yield components, plant N uptake, apparent N recovery (ANR), soil bulk density, total soil organic carbon (SOC) stock and C and N distribution between different soil organic matter (SOM) fractions. MT showed a similar grain yield to CT, while a 15 % reduction was recorded with NT, which was penalized by low plant density and high soil compaction in the surface layer. Although NT exhibited higher panicle density, spikelets per panicle, and 1000-grain weight than CT and MT, these factors were not sufficient to compensate for the grain yield gap. NT resulted in decreased plant N uptake and ANR, making increasing N fertilization in NT ineffective for recovering the yield gap with CT. After six years, no significant difference was found in SOC stock among the tillage treatments. However, conservation tillage influenced the vertical distribution of SOC, resulting in higher concentration in the superficial soil layer (0–15 cm) compared to CT. MT led to the highest amounts of labile and physically protected SOM in the 0–15 cm layer compared to NT, where lower crop residue input due to lower straw production limited the accumulation of these types of SOM fractions. MT use production resources more efficiently compared to CT and sustains soil fertility by promoting organic matter and nitrogen inputs, facilitating soil aggregation and preventing soil compaction. Yield reductions and excessive soil compaction are the main obstacles to the wide adoption of NT. Minimum tillage is a viable alternative to conven