Fertilization: There is nothing better than a correct diagnosis

Fertilization: There is nothing better than a correct diagnosis

With the support of a technical advisor, it allows the identification of changes in soil fertility and physical problems based on evidence.

Wheat reaction to fertilization
Wheat reaction to fertilization

Correct diagnosis determines fertility disorders: alkalinity, salinity, salinity and / or acidity. Also physical problems: compaction, roughness, crust, Bt horizon (textural), aeration and / or water retention. These productivity constraints are a pre-assessment and a greater hierarchy than the level of soil nutrient availability..

The Technical Advisor is the one who determines the nutrient needs of the crop based on the interpretation of the soil analysis and the potential response factors to the nutrient use (crop, expected crop, soil, climate, manufacturer’s philosophy, input / output ratio). Product – I / P). Let’s look at examples of wheat cultivation with three different diagnoses of nitrogen (N) and phosphorus (P) nutrients and their management: 1) If the soil has a small supply of N and the conclusion is 140 kg of urea is fertilized. (Ug) / ha. 2) If the soil has a high stock of N and is engaged in fertilization, 70 kg Ug / ha. 3) If it is not known how much N is in the soil and it is decided to use an average zonal dose, for example 100 kg UG / ha.

For 1 and 2 cases, decide to buy 70 or 140 kg UG / ha. Implies a value difference of $ 98 / ha. The cost of a soil test is about $ 1.2 / ha. In the case of high investment decisions such as the purchase of fertilizers, the use of inexpensive tools such as soil analysis is justified, which reduces the uncertainty of the decision. In the third case, the use of zonal mean fertilization, without diagnosis, may be insufficient, adequate or more than necessary. The success of the fertilization response will remain random. The producer may miss the crop due to insufficient fertilization or over-fertilization due to excessive increase in costs.

Impact of fertilization
Impact of fertilization
Trial comparison
Trial comparison

Let’s look at two other scenarios: 4) What happens if the soil P Bray is 20 ppm and it is decided not to fertilize. 5) What if P Bray is 12 ppm and it is decided to fertilize 20 kg P / ha = 230 kg Super Simple Phosphate (SPS) / HA. In one case in the Diamante district of Entre Rოსos, agronomic information showed that batches of P Bray were less than 15 ppm and fertilized at 20 kg P / ha. They have an average response of 700 kg tg / ha. Parties with P Bray above 15 ppm show insignificant responses, with no difference in yield. Then it turns out that for the 4th case it does not lose yields by not fertilizing, nor does it incur costs. In this campaign the crop will supply P from the soil. This consumption should be supplemented in the future to maintain soil fertility, for example when the I / P ratio is favorable. Fertilization for the 5th case involves a cost of 165 U $$ / ha. The answer is 700 kg tg / ha, equal to 217 US $ / ha. The producer receives a profit of $ 38 / ha.

Fluctuating pricing scenarios, like current ones, require knowledge technology tools. A correct diagnosis is one that helps maximize crop production and / or yields while taking care of soil resource sustainability.

The author is a member of the Technical Committee of Fertilizar AC

Source: La Nacion

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