Effect of no-tillage crop rotation systems on nutrient status of a rhodic ferralsol in southern Brazil
In this study the effects of no-tillage and eight crop rotations (established in 1985) on chemical properties of a Rhodic Ferralsol (Typic Haplorthox, Soil Taxonomy) and on nutrient uptake by maize (Zea mays L.) and soybean (Glycine max L. Merrill) leaves were assessed in the state of São Paulo, Brazil, using a randomized complete block design. The rotation crops, mucuna (Mucuna aterrima Piper&Tracy), cajanus (Cajanus cajan (L.) Millsp, rye (Secale cereale L)., oat (Avena sativa L.), pisum (Pisum sativum L.), wheat (Triticum aestivum L.), crotolaria (Crotolaria juncea L.), and black oats (Avena strigosa Scheib), were planted in winter whereas maize and soybean were planted during the summer. Each treatment was replicated three times. In 1988 soil chemical properties were measured at 0-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m depths and nutrient uptake of maize and soybean leaves was determined. Results showed that with the exception of P there was no consistent pattern in the distribution of these nutrients with soil depth. With reference to the initial values in 1985 and taking the average of the 0.0-0.30 m depth, the rotations increased all soil chemical properties, with higher values occurring on soybean than maize plots. There were highly significant negative correlations between soil pH and total acidity (r = -0.967** on maize and r = -0.958** on soybean plots) which indicate the contribution of mainly organic matter (OM) and exchange sites to the acidity of this soil. However, the contribution of OM from the crop rotations in this soil was rather poor in the short run. Also the uptake of macronutrients in 1988 varied significantly among the crop rotations and with higher values obtained in soybean than maize plots. The uptake of micronutrients by maize leaves were quite low.
Keywords: Maize; Soybean; Soil fertility; Soil chemical properties, Nutrient uptake
Agro-Science Vol. 4 (2) 2005: pp. 8-14