BACKGROUND: Biodiversity-based agricultural systems can improve production efficiency and sustainability, with fewer negative environmental impacts and lower use of external inputs. Mixed-cropping and rice-duck co-culture have been shown to produce ecological benefits and to have positive effects on paddy soil. However, the effects of a combination of mixed cropping with different rice cultivars and duck co-culture on soil nutrients availability and grain yields have not been evaluated. A paddy field experiment was carried out over two rice growing seasons to test these effects. RESULTS: Several combinations of rice cultivars, when integrated with duck co-culture, significantly increased the soil organic matter and total nitrogen contents during the rice growing seasons, as compared to mono-cropping systems. In mixed-cropping combined with duck co-culture (MCDC) systems, the soil alkali-hydrolyzable nitrogen content ranged from 4.33% to 17.86% higher than that in mono-cropping systems. Similar increases were found for soil available phosphorus (8.71-15.91%) and soil available potassium (8.65-39.43%) contents. Furthermore, MCDC produced higher grain yields and harvest indexes for both study seasons. CONCLUSION: The integration of MCDC systems had positive effects on soil nutrient contents of paddy fields, which could, in turn, lead to yield enhancements, as well as additional income for farmers in the form of organic duck meat. CONCLUSIONSMCDC systems not only improved the SOM, soil TN, AN, AP and AK contents in paddy fields, but also significantly increased the grain yield of formula rice. These advantages might be due to several factors. First, the ducks' daily activities (e.g. trampling, pecking, shaking or hitting) might have a positive effects on plant growth up to the rice heading stage. Second, the ducks ingested J Sci Food Agric 2020; 100: 277-286

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BACKGROUND: Cereal-legume intercropping systems are an environmentally friendly practice in sustainable agriculture. However, research on the interspecific interaction of nitrogen (N) between rice and aquatic legumes has rarely been undertaken. To address this issue, a pot experiment was conducted to investigate N utilization and the N interaction between rice and water mimosa (Neptunia oleracea Lour.) in an intercropping system. The root barrier patterns consisted of solid barrier (SB), mesh barrier (MB), and no barrier (NB) treatments. The N fertilizer application rates were low, medium, and high N rates. RESULTS:The results showed that the NB treatment better facilitated rice growth compared with the MB and SB treatments. And the nitrate N content and urease activity of rice rhizospheric soil in the NB treatment were the highest of the three separated patterns. The ammonium N content in water mimosa rhizospheric soil and N 2 fixation of water mimosa ranked as NB > MB > SB.CONCLUSIONS: The amount of N fixation by water mimosa was 4.38-13.64 mg/pot, and the N transfer from water mimosa to rice was 3.97-9.54 mg/pot. This can promote the growth of rice and reduce the application of N fertilizer. We suggest that the rice-water mimosa intercropping system is a sustainable ecological farming approach and can be applied in the field to facilitate rice production.

BACKGROUND Cereal cultivation with legumes plays an important role in improving biodiversity and productivity. However, there are limited references concerning rice/legume mix‐cropping in paddy fields. An aquatic leguminous plant, water mimosa (Neptunia oleracea Lour.), was introduced and a related field experiment of two seasons (early and late seasons in 2019) was carried out to explore the effects of rice/water mimosa mix‐cropping on rice growth, yield, grain quality and soil nutrients in the present study. Three treatments – rice monocropping, rice/water mimosa intercropping and mix‐cropping – were employed in this study. RESULTS Results showed that rice grew better with greater height, tiller number, chlorophyll content, actual photosynthetic efficiency [Y(II)], maximum photochemical efficiency (Fv/Fm) and photochemical quenching coefficient (qP) in the intercropping and mix‐cropping treatments. In addition, the intercropping and mix‐cropping treatments increased nutrient uptake of nitrogen (N) by11.89–24.42%, phosphorous (P) by 17.75–36.61% and potassium (K) by 19.22–47.44%, and rice yield by 19.9% and 21.8%. Conversely, the non‐photochemical quenching coefficient (NPQ), chalkiness degree and chalky rate of rice were lower in the intercropping and mix‐cropping treatments relative to those in the monocropping treatments. Notably, soil alkali‐hydrolysable N (AN), available P (AP) and K (AK) contents were the highest in the mix‐cropping treatments among the three cropping systems. CONCLUSION We suggest that rice/water mimosa mix‐cropping is an environmentally friendly agroecological system with a higher output and can be extended for green rice production and largely applied in the paddy field. © 2021 Society of Chemical Industry.

BACKGROUND Previous studies found that mixed cropping combined with duck co‐culture (MCDC) system could improve the efficiency of grain production and positively affect soil nutrient contents. However, the effects on grain quality, and profitable income have not been evaluated yet. In this study, a field experiment with four combinations of different rice varieties and ducks was conducted during both the early and late rice growing seasons. RESULTS The field survey demonstrated that MCDC system significantly decreased the grain appearance of chalky rice rate and the chalkiness degree with an average of 56.82%, and 54.28%, respectively. Leaf SPAD value, photosynthetic rate, and aboveground dry weight were all improved in the MCDC and mixed‐cropping systems, relative to the mono‐cropping system. The net income obtained from the mono‐cropping, mixed cropping (no ducks), and MCDC (with ducks) systems (from grain and ducks' meat) was 581.2 USD ha−1 yr−1, 1001.8 USD ha−1 yr−1, and 5242.1 USD ha−1 yr−1 in both growing seasons, respectively. CONCLUSION Planting genetically diverse rice varieties and co‐culture with ducks increased rice growth rates, productivity and grain quality. The MCDC system would provide more ecological and economic benefits compared with the conventional mono‐cropping system. © 2022 Society of Chemical Industry.

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Cereal/legume intercropping is an effective agricultural practice for pest and disease control and crop production. However, global research on rice and aquatic legume intercropping is relatively rare. A field experiment during two seasons (2018 late season and 2019 early season) was conducted to explore the effects of rice and water mimosa intercropping on rice canopy microclimate, pest and disease, yield, grain quality, and economic income. Two cultivation patterns including rice/water mimosa intercropping and rice monocropping were employed, and three nitrogen (N) fertilizer application levels, including zero N (ZN, 0 kg ha−1 N), reduced N (RN, 140 kg ha−1 N), and conventional N (CN, 180 kg ha−1 N) levels, were applied for the above two cultivation patterns. The results showed that rice/water mimosa intercropping formed a canopy microclimate of rice with higher temperature and lower relative humidity and dew point temperature. In addition, there was a significant reduction in the occurrences of rice leaf blast by 15.05%~35.49%, leaf folders by 25.32%~43.40%, and sheath blight by 16.35%~41.91% in the intercropping treatments. Moreover, rice/water mimosa intercropping increased rice per unit yield by 43.00%~53.10% in the late season of 2018 and 21.40%~26.18% in the early season of 2019. Furthermore, rice grain quality was totally improved, among which brown and head rice rates increased but rice chalky rate and chalkiness degree decreased in the intercropping system. We suggest that combining rice/water mimosa intercropping and N fertilizer reduction can be used as an environmentally friendly eco-farming technique because it can decrease N fertilizer application by approximately 40 kg·ha−1. This combination would not only mitigate nonpoint source pollution but also obtain advantages for controlling rice pests and diseases that would alleviate pesticide usage and improve rice yield and grain quality, which can be extended for green rice production to increase income for producers.