In conventional agriculture, weed control by herbicides is an expensive practice and can also have a negative effect on the environment. Allelopathy permits sustainable weed management while reducing the impact of agriculture on the environment. We studied the content of 2,4-dihydroxy-1,4 (2H)-benzoxazin-3-one (DIBOA) and benzoxazolin-2(3H)-one (BOA), indicated as benzoxazinoids and considered effective for weed control, in 8 cultivars of rye and 1 of triticale grown in a greenhouse. We also tested the ability of mulches to inhibit the germination of four warm-season weeds. Our results show that all rye cultivars produced DIBOA, while BOA was found only in four of them. Benzoxazinoids were absent in triticale. Total benzoxazinoid content ranged from 177 to 545 µg g −1 and was statistically different among cultivars. Rye mulches were not able to suppress velvetleaf and common lambsquarters seedlings, while redroot pigweed and common purslane were significantly affected. Weed suppression ranged from 40% to 52% for redroot pigweed and from 40% to 74% for common purslane. The inhibitory activity of triticale mulch was observed only for common purslane, with a suppression percentage of 33%. No correlation was found between total benzoxazinoid content and the number of weed seedlings suppressed, with R 2 of 0.076 for redroot pigweed and R 2 of 0.003 for common purslane, indicating that benzoxazinoids are not the only source of phytotoxicity. allelopathy / BOA / DIBOA / integrated weed control / mulch / rye / triticale

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BACKGROUND: Fusarium ear rot and fumonisin contamination are serious problems for maize growers. The lack of maize genotypes highly resistant to fumonisin contamination emphasises the need for management strategies to prevent contamination by this mycotoxin. There are conflicting reports regarding no-till and nitrogen (N) fertilisation practices in relation to the incidence of fumonisins. In this study the effect of no-till compared with conventional tillage and of N fertilisation rates on fumonisin occurrence was investigated over three years in Northern Italy.

An experimental trial was carried out over three years at Cavacurta (Po valley, Italy) on continuous barley. The soil was a coarse-loamy over sandy, mixed, mesic Fluventic Ustochrept. The experimental design was a split-plot with four replicates; the main factor was the soil management system (conventional tillage, CT, and no-tillage, NT), while the secondary factor was the nitrogen fertilization (N 0 = 0, N 1 = 50 and N 2 = 90 kg N ha -1 year -1 ). At the end of the third year soil samples were taken in all plots at four depths (0-5, 5-10, 10-15 and 15-20 cm). For these samples, pH, organic matter, total N, available P and cation exchange capacity were determined. On the contrary, water aggregate stability was determined for a single layer (0-20 cm depth), excluding the N 1 level of fertilization. The biological indicator, QBS-ar index, was studied only in the layer 0-10 cm. Statistical analysis shows that no-till positively influenced all the indices except for CEC and QBS-ar. N fertilization had significant effects on CEC only; in the upper layer, the value in N 2 subplots was of approx. 1 cmol + kg -1 higher than in N 0 and N 1 subplots. There was no significant interaction for any of the indices. As regards only the 0-20 cm layer, the most important results are as follows. The organic matter content in NT plots was significantly higher than in CT plots (32.6 vs 29.8 g kg ). No-till also had a very clear effect on the Olsen-P (12.3 vs 9.3 mg kg -1 ). The most remarkable result was found for the water aggregate stability: for NT plots the value was 246% higher than for CT plots (34.3 vs 9.9%). As regards the microarthropod community, the value of the QBS-ar index was between 90 and 126, a typical range for soil under barley.

A three-year (2004-2006) field trial was carried out to compare two agricultural land management systems, in the Po Valley (Northern Italy). Conventional tillage and No-tillage (hereafter indicated as CT and NT, respectively) were compared for maize treated with three levels of nitrogen. The soil was a fine-loamy, mixed, mesic Ultic Haplustalf, that had been under processing tomato in the previous year. Experimental design was a split-plot with four replicates, with the management system as the main factor and nitrogen fertilization (0, 250 and 300 kg N ha-1 year-1) as the secondary factor. Cumulative 3-yr yields of grain and total biomass of NT maize plants were 8% lower than those obtained under CT management, but not significantly different. No N starter was distributed in the first conversion year, causing 17% less grain yield in the NT plots compared with the CT plots. The N fertilizing with 250 and 300 kg N ha-1 year-1 determined statistically equal grain yields, demonstrating the waste of the extra 50 kg N at the N2 rate. Overall, the results for the three years indicate that on an Ultic Haplustalf conversion from a ploughed regime to mature NT conditions could be achieved over a relatively short period