Combined use of contrasting quality organic residues and chemical fertilizers for corn growth in a sandy soil

บทคัดย่อ

A plant bioassay experiment was conducted to evaluate the effects of residue quality (chemical composition
with respect to N, lignin, and polyphenol contents), chemical fertilizers, and their interactions, on plant nutrient availability and growth. Corn plants were grown in pots containing sandy soils taken from a long-term field experiment in which five levels of contrasting quality residues were applied annually for 20 years. The residue treatments included: (i) unamended (control, CT), (ii) rice straw (RS), (iii) groundnut stover (GN), (iv) dipterocarp freshly fallen leaf litter (DP), and (v) tamarind freshly fallen leaf and petiole litter (TM). The soils from the field experiment were treated with 2 different chemical fertilizer management practices with (70.3 N, 30.7 P, and 58.4 K kg/ha) or without fertilizers. Under the sole residue treatments, only high-quality GN [N-rich (21 g/kg)] produced a significantly higher biomass than CT. However, for the residue plus fertilizers treatments, all the residues significantly increased biomass relative to CT, with the highest biomass found in GN. Similar results were found in plant uptake of N and P. TM did not enhance growth to the same extent as GN due to the lower quality of TM [low N content (12 g/kg) and high polyphenols]. For the high-K residues GN (25 g/kg) and RS (14), GN had resulted in lower concentration and uptake of K in the plants than RS. For low-K residues, TM (6 g/kg) and DP (4), TM produced a lower concentration and uptake of K than DP. Both legume residues had a high Ca content (21 and 35 g/kg, respectively). This produced a high Ca/K ratio of 2 and 7 under GN and TM, respectively. These values were higher than the Diagnosis and Recommendation Integrated System (DRIS) norm ratio of 0.3. The antagonistic effects of Ca on K are discussed.