Upland rice intercropped with green manures and its impact on the succession with common bean

The aim of this work was to verify the possibility of intercropping rice with green manures, as well as the impact of the dry biomass yield of these intercropping systems on common bean in succession, evaluating the agronomic and qualitative performance of grains from both crops. The experiment was conducted in Southeastern Brazil in the years 2018 and 2019, with succession of rice (spring/summer) and common bean (autumn/winter). The treatments were composed of cropping systems with rice as a sole crop and intercropped with forage peanut, calopo, Crotalaria breviflora, Crotalaria spectabilis, stylo, jack bean and dwarf pigeon pea. No intercropping increased the system's yield compared to sole-crop rice, but intercropping of rice with forage peanut and stylo promoted grain yield and quality similar to those of sole-crop rice. Intercropping with C. breviflora affected the agronomic and qualitative performance of rice. Common bean yield after rice intercropped with dwarf pigeon pea, C. spectabilis and C. breviflora was similar in yield after sole-crop rice, while the other intercrops reduced common bean yield. Common bean grain quality was not affected by the cultivation of rice as sole crop and intercropped with green manures. Although none of the intercropping systems increased yield compared to sole-crop rice (control), it can be concluded that the intercropping of upland rice is viable depending on the green manure species, allowing greater biomass production per area that can help long-term soil conservation and increase the system's yield.

Beetroot and radish production under different doses of green manures

Green manuring with spontaneous species from Caatinga biome has become an important strategy in production vegetables. One of the great challenges in tuberous vegetables production is to define an optimized quantity that provides a high productive yield with economic efficiency of production system. The objective of this study was to optimize agronomically and economically the production and its components of tuberous crops of beetroot and radish when manured with different amounts of green manures biomass, Merremia aegyptia and Calotropis procera from Caatinga biome, in two cropping seasons. The experimental design was a randomized complete block with five treatments and five replications. Treatments consisted of green manures amounts (16, 26, 36, 46, 56 t ha-1). The maximum agronomic efficiency of beetroot and radish was obtained with incorporation of 49.87 and 39.43 t ha-1 of M. aegyptia and C. procera, respectively, and the production maximum economic efficiency was reached when 36.14 and 36.48 t ha-1, respectively, of biomass of these green manures were added to the soil. The returns rate obtained in beetroot and radish cultivation using the manures optimized amounts were 1.42 and 1.32 reais obtained for each real invested in the production of these tuberous.

Use of Crop Rotations, Cover Crops and Green Manures for Disease Suppression in Potato Cropping Systems

Crop rotations and the inclusion of cover crops and green manures are primary tools in the sustainable management of soil-borne diseases in crop production systems. Crop rotations can reduce soil-borne disease through three general mechanisms: (1) serving as a break in the host-pathogen cycle; (2) by altering the soil physical, chemical, or biological characteristics to stimulate microbial activity and diversity; or (3) directly inhibiting pathogens through the release of suppressive or toxic compounds or the enhancement of specific antagonists. Brassicas, sudangrass, and related plant types are disease-suppressive crops well-known for their biofumigation potential but also have other effects on soil microbiology that are important in disease suppression. The efficacy of rotations for reducing soil-borne diseases is dependent on several factors, including crop type, rotation length, rotation sequence, and use of the crop (as full-season rotation, cover crop, or green manure). Years of field research with Brassica and non-Brassica rotation crops in potato cropping systems in Maine have documented the efficacy of Brassica green manures for the reduction of multiple soil-borne diseases. However, they have also indicated that these crops can provide disease control even when not incorporated as green manures and that other non-biofumigant crops (such as barley, ryegrass, and buckwheat) can also be effective in disease suppression. In general, all crops provided better disease control when used as green manure vs. as a cover crop, but the addition of a cover crop can improve control provided by most rotation crops. In long-term cropping system trials, rotations incorporating multiple soil health management practices, such as longer rotations, disease-suppressive rotation crops, cover crops, and green manures, and/or organic amendments have resulted in greater yield and microbial activity and fewer disease problems than standard rotations. These results indicate that improved cropping systems may enhance productivity, sustainability, and economic viability.

Alternative methods for terminating green manures in organic grain systems

Legume green manures (GM) are a vital source of nitrogen (N) for many organic grain systems. A common practice among organic growers is to undersow clover into a small grain, harvest the grain crop and terminate the clover stand in late fall by moldboard plowing in preparation for a cash crop the following spring. While fall plowing offers excellent clover kill, growers increasingly seek an alternative termination method that reduces tillage intensity and bare winter soil. This study, performed at two sites in Maine, evaluates three clover termination methods for kill efficacy, winter soil cover, spring soil conditions and N uptake and grain yield and protein of a subsequent test crop of hard red spring wheat (Triticum aestivum L., var. Glenn). Red clover (Trifolium pratense L.) was intercropped with spring barley (Hordeum vulgare L.) and terminated in late fall by moldboard plowing (PL), skim plowing (SK) or undercutting (UC). A control treatment received no clover and was fall plowed. An additional treatment, winterkilled field peas (WK), was evaluated at one site. SK, UC and WK increased soil cover relative to PL, though UC resulted in low clover kill efficacy in a wet spring and is in need of improved design. Grain yield was higher following red clover compared to the no-clover control at one site, but was unaffected by termination method. At one site, grain crude protein was higher following PL than the other treatments, indicating the possibility for more favorable timing of N availability associated with PL.

Effects of green-manure and tillage management on soil microbial community composition, nutrients and tree growth in a walnut orchard

This study characterized the effect of green manures (February orchid, hairy vetch, rattail fescue and a no-green-manure control) and the termination method (flail or disk) on nutrient contents, enzyme activities, microbial biomass, microbial community structure of rhizosphere soil and vegetative growth of walnut tree. All three selected green manures significantly enhanced the water content, organic C, total N and available P. The rattail fescue significantly decreased the mineral N. Total organic C, total N, mineral N and available P were significantly greater under flail than under disk. Hairy vetch and February orchid significantly improved levels of soil β-glucosidase, N-acetyl-glucosaminidase and acid phosphatase activity, whereas rattail fescue improved only β-glucosidase activity. All of the green manures significantly decreased phenoloxidase activity. β-glucosidase, N-acetyl-glucosaminidase and acid phosphatase activities were significantly greater under flail relative to disk. The termination method had no significant effect on phenoloxidase activity. The different types of green manures and termination methods significantly altered the soil microbial biomass and microbial community structure. The green-manure treatments were characterized by a significantly greater abundance of Gram-positive (Gram +) bacteria, total bacteria and saprophytic fungi compared to the control. Hairy vetch significantly decreased the abundance of arbuscular mycorrhizal fungi (AMF) while February orchid and rattail fescue increased their abundance compared to the no-green-manure treatment. The abundance rates of Gram+ bacteria, actinomycetes, saprophytic fungi and AMF were significantly greater in soils under flail than under disk. In terms of vegetative growth of walnut tree, hairy vetch showed the greatest positive effects. The growth of walnut tree was significantly greater under flail relative to disk. Our results indicate that green-manure application benefits the rhizosphere soil micro-ecology, rhizosphere soil nutrient contents and tree growth. Overall, the hairy vetch and flail combined treatment is recommended for walnut orchards in northern China.