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La soja absorbe una gran cantidad de potasio, totalizando cerca de 21 kg Klt de
grano de soja. As, para una soja de altos rendimientos, los productores deben prestar
atenci6n a los niveles de K indicados por los and/isis de suelo y optimizar las prcticas.de
manejo de K para optimizar los beneficios
NUTRIENT MANAGEMENT IN NO-TILLAGE
SOYBEAN PRODUCTION
Soybean production using no-tillage techniques is increasing rapidly throughout
the world. Nutrient management, especially the immobile phosphorus (P) and potassium
(K) nutrients, is an important factor necessary to sustain long-term no-till soybean
production. In contrast to conventional tillage systems where nutrients can be incorporated
easily with tillage operations, alternative application and placement methods must be
developed and evaluated to optimize nutrient uptake and soybean production in no-tillage
systems.
This paper will discuss no-till soybean production from the following standpoints:
(1) yield comparisons between no-671 and various tillage systems across varying soil
characteristics using high-fertility management practices, (2) stratification of P and K near
the soil surface in no-till systems, (3) effect of soil test P and K levels on no-till soybean
yield response to fertilizer, (4) effect of P and K placement methods on no-till soybean
production, and (5) uptake of P and K by soybeans as affected by tillage practices and
fertilizer P and K placement. Most of the information presented will be based on studies
conducted within the Com Belt of the United States.
Soil characteristics such as texture and internal drainage can affect no-till soybean
production. Soybean yields have not been affected by tillage systems following maize on
medium textured, well-drained soils. However, on more poorly drained, fine-textured soils
no-till soybean yields can be 0.3 Mg/ha less than for conventional tillage, especially in the
northern latitudes (above 400).
Stratification of P and K commonly exists in no-till production systems. High levels
of soil test PandKare foundnearthe soilsurface with substantially lower levels below 10
to 15 cm. The effect of this stratification on soybean production as influenced by soil test
level will be discussed.
Soybean yields have not been affected greatly by P and K placement methods in
no-till systems. Phosphorus placement methods have generally not affected soybean
yield. However, in low-P testing soils large soybean yield responses to residual P remaining
from fertilizer P applied for the previous maize crop have occurred, regardless of P
placement method. Extensive studies in Iowa showed soybean yields to be slightly greater
for deep-banded K compared to surface broadcast or planter-band starter K, even on
high-K testing soils.
Potassium uptake by soybean is very high, totaling about 21 kg K/Mg of soybean
grain. Thus, with high soybean yields, farmers must pay attention to soil test levels and K
management practices if profits are to be optimized.
Sesi6n IV. ApIicaci6n y uso de fertiizantes podsicos
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