**5. Final considerations**

threshing and drying. This minimizes crop risk and optimizes use of resources such as water, labor, fertilizer, herbicides and insecticides. Knowledge of the critical periods for crop development in conjunction with knowledge of climatic factors is very helpful for adjusting

A Comprehensive Survey of International Soybean Research - Genetics, Physiology, Agronomy and Nitrogen

As already highlighted climate stresses such as drought, excessive rain, extreme temperatures and low irradiance can significantly reduce yields of crops and restrict areas and timings of production. The most important factors useful to know for soybean production are air

In Brazil, a system has been developed for identification of suitable areas for planting soybean. The Agricultural Zoning Program has been coordinated by the Ministry of Agriculture and EMBRAPA since 1996. This program has the objective of defining planting seasons guarantee at least an 80% probability of having an adequate water supply for the growing season. The planting periods were defined through the simulation of a climatic water balance that gives an index of water supply called by the Portuguese initials as ISNA (Water Necessity Satisfac‐ tion Index) using historical rainfall data, potential evapotranspiration, physiological charac‐

Since 1988, agricultural scientists have been studying climate change mainly according to the rules of IPCC (Intergovernmental Panel on Climate Change). In recent years global studies have shown consistent changes in air temperature and rainfall in many places of the world [17, 18]. The Earth's average temperature can rise between 1.8ºC and 4.0ºC in the next 100 years [19] with more significant increases for minimum than maximum air temperature. However, in the case of South America temperature trends may not be consistent [20]. Contemporary scientific studies have warned of anomalies in temperature and precipitation patterns indicating the occurrence of global change, with direct consequences on human activities, especially those

Globally, agriculture accounts for 23% of all emissions of greenhouse gases (GHG) that come from human activity. Parts of these (15%) are derived from agricultural practices and the other part (8%) is from changes in land use [21]. However, in Brazil a greater proportion of agricul‐ ture's contribution to GHG comes from agricultural practices [22]. Soil is also an important source of carbon emission and sequestration [23]. Soil management practices affect to what degree these processes go on. Conventional tillage operations tend to increase carbon release to the atmosphere, whereas conservation tillage and crop rotation with their increased contribution of crop organic matter to the soil tend to increase carbon sequestration [24]. These practices also improve the physical, chemical, and biological balances in the soil. Current agriculture through its production of fiber, bioenergy and food reduces pollution and mitigates

A good example are the results of a research carried out at Embrapa Soja (Londrina, PR, Brazil) for levels of Carbon (C) and Nitrogen (N) in soil under no-tillage (NT) and conventional sowing

management practices for best crop yield and quality.

Relationships

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temperature, photoperiod and water supply [10].

teristics of each crop and water retention by the soil [16].

**4. Climate change: A challenging**

related to agricultural production [18].

GHG emissions [25].

Currently inside the world agriculture, the increases of yields and the reduces of the costs and risks from failure, have become the basic requirements of competitive. Besides, in terms of economic activity with narrow profit margins, there is no room for risk.

Immense progress has been achieved, adapting the soybeans to obtain high levels of incomes in areas of lower latitudes. The photoperiod limitation was eliminated by the careful selection and also the development of the germoplasma less sensitive to photoperiod. The yields are extremely dependent of the water available and probably are also necessary to increase it to meet the crop transpiration and the productivity enhancement.

Environmental forecasts signaling the increase of the temperatures in the upcoming decades which mean the climate change. The difficulty to feed the world population, (which is in growing fast) using only traditional technologies will be immense shortly. The development of variety tolerant to adverse climatic conditions such as drought and high temperatures, it will be essential, as well as the development of new research tools in the areas of plant biotechnology and ecophysiology. It will enable us to understand the details of the processes involved in physiological and agronomic crops. Only with the development and continued growing in agricultural research, you can ensure food quality and quantity for future gener‐ ations.
