Abstract Phosphorus (P) is one of the main nutrients for all plants, including grasses. However, sources of P fertilizer are not renewable, are not evenly distributed and overfertilization can lead to serious environmental degradation. Smart combinations of grasses may be able to more efficiently take up P from soils through complementarity. In a two-year field mesocosm experiment, we compared the performance of Lolium perenne L. and Festuca arundinacea Schreb. in monocultures and in combination, as well as a mixture of both species with a tetraploid variety of Lolium perenne L and Phleum pratense L. Plants were grown in an unfertilized low P soil and in P fertilized soil for two growing seasons. We measured biomass production, root traits, nutrient uptake, microbial biomass and enzymatic activities. In the unfertilized plots the combination of Lolium perenne and Festuca arundinacea generated the highest cumulative yields (25,951 ± 4059 kg ha−1), relative total yield (> 1) and P nutrition index (0.79). We related this to the complementarity found in root traits and lower intraspecific competition of Festuca arundinacea and Lolium perenne diploid. Festuca arundinacea produced higher root biomass than Lolium perenne diploid at deeper soil layers (98 vs. 44 g m−2; p < 0.05). On the other hand, Lolium perenne diploid had significantly finer roots than Festuca arundinacea both at topsoil and bottom layers (0.19 vs. 0.22 mm and 0.19 vs. 0.23 mm at top and bottom layers respectively). The 4 species combination did not result in higher yields. Our results show that, in low P soils, combinations of grass species with contrasting root traits could lead to significantly higher yields than monocultures.

Stricter nutrient surplus and lower emission targets are placing adaptation pressure on livestock farms in European countries, while the public debate on how farms should react upon this pressure is controversial. In this paper, we performed an integrative literature review on different farm adaptation options, including (i) structural adaptation, (ii) technological adaptation, (iii) manure redistribution, and (iv) farm system conversion. Our analysis showed that stricter environmental legislation, together with complementary supply- and demand-related drivers, induced various farm responses. These ranged from easy to implement solutions (e.g. moderate livestock destocking to the legal levels combined with the adoption of emission abatement technologies) to novel niche concepts (e.g. animal husbandry without slaughtering). Possible reactions of farmers differed in their complexity and feasibility across different farm types and involved different trade-offs between environmental and socioeconomic interests. Future livestock production is expected to be diverse with different coexisting models that combine features of different adaptation options. The private and public sustainability of these models depends on their ability to simultaneously address multiple emerging challenges (e.g. emission reduction, animal welfare, biosecurity, and circularity). Current technological solutions often focus on a single objective (e.g. emission reduction). Integrated and multifunctional solutions (e.g. low-emission animal welfare barns compatible with biosecurity measures) are not yet sufficiently adopted, which calls for a rethinking and shifting in priorities in legislation and funding schemes.

Rapid urbanization in many countries of the Global South has led to intensification of urban and peri-urban agriculture (UPA) whose effects on the soils’ physical, chemical, and microbial properties have been hardly studied. We therefore investigated the effects of different intensity levels, exemplified by three rates of mineral nitrogen (N) addition and irrigation on CO2 emissions in typical crops during the wet (Kharif) and dry (Rabi) season on a Nitisol in Bengaluru, S-India. Respiration data were collected from 2017 to 2021 in two two-factorial split-plot experiments conducted under rainfed and irrigated conditions. Test crops were maize (Zea mays L.), finger millet (Eleusine coracana Gaertn.), and lablab (Lablab purpureus L. Sweet) under rainfed and irrigated conditions, as well as the vegetables cabbage (Brassica oleracea var. capitata), eggplant (Solanum melongena L.), and tomato (Solanum lycopersicum L.) or chili (Capsicum annuum L.). Carbon dioxide (CO2) emissions were determined using a Los Gatos Research (LGR) multi-gas analyzer whereby under our study conditions CH4, NH3 and N2O were negligible. Measurements were conducted from 7:00 am to 11:30 am and repeated from 12:30 pm to 6:00 pm. Irrespective of irrigation, season, crops and N fertilizer level, CO2 emission rates during afternoon hours were significantly higher (2–128%) than during morning hours. In the irrigated field diurnal emission differences between afternoon and morning hours ranged from 0.04 to 1.61 kg CO2-C ha−1 h−1 while in the rainfed field they averaged 0.20–1.78 kg CO2-C ha−1 h−1. Irrespective of crops, in the rainfed field CO2 emissions in high N plots were 56.4% larger than in low N plots whereas in the irrigated field they were only 12.1% larger. The results of a linear mixed model analysis indicated that N fertilization enhanced CO2 emissions whereby these effects were highest in rainfed crops. Soil moisture enhanced emissions in rainfed crops but decreased them under irrigation where crop-specific CO2 emissions within a season were independent of N application. Soil temperature at 5 cm depth enhanced CO2 emissions in both fields. Overall, higher N and soil temperature enhanced CO2 fluxes whereas effects of soil moisture depended on irrigation.

Phosphate-solubilizing bacteria represent a bioalternative in making soil-immobilized phosphorus (P) available to plants, and consequently improve agriculture sustainability and reduce nutrient pollution. In this study, we examined whether Rhizobium sp. B02 inoculation can affect the soil P fractions. Moreover, we investigated how inoculation influences the growth, physiological traits, and productivity of the maize crop. Field tests were carried out to evaluate the combined application of strain B02 and reduced doses of P fertilizer. Soil P fractionation was performed after crop harvesting, assessing the P dynamics. To study the plant response, samplings were carried out in three phenological stages—the vegetative stage of the 7 fully emerged leaves with leaf collars (V7), the vegetative stage of the tassel (VT), and the reproductive stage of physiological maturity (R6). Using 50% of P fertilizer recommended, the strain inoculation increased the labile inorganic P fraction by 14% compared to the control treatment at the same dose, indicating that it favored the Pi mobility. Under these same conditions in the V7 and VT phenological stages, the inoculation significantly improved shoot length (28 and 3%) and shoot dry weight (9.8 and 12%). B02 inoculation increased grain yield by 696 kg ha−1 using 50% of the recommended rate of P fertilizer, phenocopying the complete P fertilization treatment without inoculation. Therefore, Rhizobium sp. B02 inoculation replaced 50% of P fertilizer in maize and increased the soil P availability.