ABSTRACT.- The UK Government has set an ambitious target of achieving a national "net-zero" greenhouse gas economy by 2050. Agriculture is arguably placed at the heart of achieving net zero, as it plays a unique role as both a producer of GHG emissions and a sector that has the capacity via land use to capture carbon (C) when managed appropriately, thus reducing the concentration of carbon dioxide (CO2) in the atmosphere.

After more than 20 years from its departure point in Beijing 2000, the Symposium lands for the second time in South America, where it will tackle the issues of the current P cycle, in the agroecosystems of the region but also of the world. On one hand, many agroecosystems in the world, such as South American one, face phosphorus scarcity for sustaining economically viable levels of primary and secondary production.

The objective was to evaluate the relationship between P balance (P fertilization minus P removal in grain) on the evolution of soil P availability (P Bray I analysis).

The specific objective is to study the effect of previous P fertilization on P fixation according to soil type.

This study investigates the co-inoculation of soybeans with rhizobia and PMB Bacillus strains with and without addition of P fertilizer on plant P uptake and crop yield.

Pasture response to N fertilization and the nitrogen use efficiency (NUE) is highly conditioned by the phosphorus (P) availability and soil water. The objective of the study was to evaluate the effect of NP fertilization on the NUE of annual ryegrass, in two growth periods.

Current sustainability challenges of production systems require comprehensive answers with a multidimensional approach. The objective of this study is to select indicators that allow quantifying the productive-economic, social, and environmental evolution of dairy systems transitioning towards agroecology through a co-innovation approach.

Nutrients deficiencies - mainly phosphorus (P) and nitrogen (N) - often depress forage productivity (FP) in pasture-based systems in the Pampas region (Argentina). Fertilizations are often used to attenuate these deficiencies, but it is necessary to increase the use efficiency of the applied nutrients.

Uruguayan dairy farms underwent an important intensification process during the last decades. Although pasture-based grazing systems are still dominant, one important component of such intensification is the increase of extra-farm feed inputs, along with an increased stocking rate and an increased supplementation rate per cow.

Several actions have been carried out in the Santa Lucia River basin (1.343.300 ha) in order to reduce the impact of anthropogenic pressure and improve water quality. Environmental models may be used as supportive tools when assessing the effect of local actions at a basin scale.