The fine one is made with the ground, the thick one with the sky. Few producers measure the water in the soil, a key data to minimize the effects of lack of rainfall. It would seem that all decisions associated with water are beyond the reach of farmers. It is not!
Agtech Argentina S4, developer of technology to reduce climate risk in agriculture, presented its September Climate Report, prepared by Carlos di Bella, responsible for R&D at S4.
The main conclusion of the report is that the majority of producers do not measure or analyze the water they have in their water tables, which is fundamental to know when to sow the coarse crop, and to minimize the effects that the lack of rain has on crops.
The phrase campera that titles this note is true: the water accumulated in the soil defines the water availability for winter crops, while for summer crops, in addition, contributions from rainfall will be necessary throughout the growing season. Taken literally, it would seem that all the decisions associated with WATER are beyond the reach of farmers. It is not so!
In the current context of enormous inter-annual and seasonal variability of rainfall, with erratic depths of water tables and with the knowledge and technologies available in crop management, it is essential to adapt to changes in climate and water availability in soil profiles to reduce, in part, the possible effects of lack of water.
In a very simplified water balance scheme, the main entry of water into the system is by rain, although in some environments and under certain conditions, groundwater can also play an important role. On the other hand, the transpiration of plant tissues and soil evaporation, integrated under the term Evapotranspiration (ET), represents, also in a simplified way, the most forceful outlet of water from the system. It is then, from the balance between outlets and inputs that the soil plays a fundamental role in storing and making available this precious resource in dryland systems.
What producer today does NOT consult short and medium term forecasts to estimate water inputs and make decisions with them? What will the rains be like during the summer? Will we have a boy, a girl or a neutral year? A very high proportion keeps records of rainfall (inputs) or speculates about the probability of occurrence of rainfall in the medium and long term to decide the sowing date, variety or growth cycle of a given crop.
Now, how many producers keep an updated record of the availability of water in the soil? How many calculate the useful water in the soil profile? How many make a water balance in the soil between the availability and probabilities of rain occurrence? How many speculate about the level of yield to reach or the best date to plant based on these measurements and estimates? The answer: VERY FEW. In comparative terms, it is like undertaking a medium-term investment and not knowing about savings tales I have available in case of need.
In today’s agriculture we cannot afford these luxuries. There is no margin for errors and unforeseen events. For example, for a field in the core zone of Buenos Aires, the normal rainfall climatology is 450 mm (as expected this year) for the September-February period with an 80% probability of occurrence (See Figure I). A soybean crop, on average, consumes 640 mm of water if it is sown in November and there is no water or nutritional deficit. It is not difficult to realize, then, that to obtain good yields it is essential to have a good supply of soil water. And for it, we suggest to realize suitable analysis of soils and to estimate the water in the profile of periodic way to make the forecasts of water reserves in the soil and to take better decisions.