Performance of Year-Round Cropping Systems on Three Tropical Soil Families

Abstract

A favorable climate throughout the year as well as the prevailing socio-economic conditions in the tropics are ideal for multiple cropping in time and space. Despite of its relevance, year-round cropping systems have seldom been used to evaluate the productivity of well-characterized tropical agroenvironments. The major objectives of this study were to monitor the effects of agroclimatic parameters on the performance of various crops and sequences of crops, and to investigate the possibility of stratifying crop production potential, on the basis of the soil family category of Soil Taxonomy, in the tropics. Year-round cropping patterns were tested on a weather-monitored network of ten sites located in Indonesia, The Philippines and Hawaii representing the tropical soil families of thixotropic, isothermic Hydric Dystrandepts; clayey, kaolinitic, isohyperthermic Tropeptic Eutrustox and clayey, kaolinitic, isohyperthermic Typic Paleudults. The cropping patterns used were specifically designed for each of the three agroenvironments and similar management practices were followed on all sites. The sequential cropping pattern of Irish potato followed by soybean and then by field corn, designed specifically for the Tropeptic Eutrustox agroenvironment, gave the highest calorie and protein yield (46581 k cal/ha and 2101 kg/ha, respectively) at the Eutrustox site of Waipio, Hawaii. The above cropping pattern also resulted in higher calorie and protein production at the Dystrandept site in Kukaiau, Hawaii compared to the specifically-designed pattern of Irish potato and vegetables followed by vegetables and then followed by soybean and peanut. The Dystrandept sites in Indonesia and The Philippines had lower yield potential compared to the site of Kukaiau, mainly because of higher temperatures of the former that resulted in low yields of vegetables and Irish potato. Head cabbage, mustard cabbage, Irish potato, carrot and bushbean were found to be susceptible to high temperature and excess moisture. The yields of the above crops were highly correlated (r = -0.70**) with soil temperature at 10 cm, and their best yields were obtained within a soil temperature range of 18 to 23°C. In contrast, soybean and peanut were adapted to a wide range (21 - 28°C) of air temperature and soil moisture. Soybean planted during April-May (long days) gave significantly higher yields compared to August-September (short days) plantings. Multiple regression equations with agroclimatic parameters as independent variables, were derived to predict yields of crops. Except for green corn, only crops that were sensitive to temperature and excess moisture (mustard cabbage, head cabbage, carrot, bushbean and Irish potato) had prediction equations with coefficients of determination close to 0.80. However, for soybean and peanut the best models incorporating as many as six environmental parameters explained less than 50 percent of the yield variability. In the Hydric Dystrandepts and Typic Paleudults (udic moisture regime), most crops grown year-round did well without irrigation. Crop performance in Tropeptic Eutrustox confirmed the absolute necessity of supplemental irrigation for year-round crop production under an ustic moisture regime. Response to Rhizobium inoculation as reflected by soybean yields, was variable. However, the number of significant responses to inoculation was greater in the Tropeptic Eutrustox than in Hydric Dystrandept sites. Bushbean yields were significantly higher in the "bushbean + mustard cabbage" intercrop combination then in the "bushbean + green corn" combination. Air tenperature was negatively correlated (r = -0.96**) with the number of days required for maturity of Irish potato. In this study, segregation of a soil family based on crop performance was possible only in case of lypic Paleudults. High average air and soil temperatures (> 26°C) prevalent in the Paleudults resulted in poor performance of temperature-sensitive crops such as head cabbage, mustard cabbage, Irish potato and carrot.