Types of Carbon Compounds That Accumulate Under No-Tillage In Rice-Based Rotations.

In a long-term field experiment of rice-based rotations near Stuttgart, AR, no-tillage promoted carbon and nitrogen sequestration in the plow layer compared to conventional tillage.  The increased amounts of carbon and nitrogen sequestered with no-tillage varied by crop rotation, ranging from about 10% increase for continuous rice to about 20% for rice-soybean.  The amount of soil carbohydrates also increased with no-tillage compared to conventional tillage, and in proportions that varied by rotation, varying from 11% increase with continuous rice to 28% increase with rice-soybean.  The proportions of plant and microbial carbohydrates under no-tillage did not differ from those with conventional tillage. Soil phenol contents also increased somewhat, especially for cinnamic phenols, which are common in grassy plants such as rice.  Results for amino acids will be discussed.