Understanding and Managing the Late Time of Ratooning Effect on Cane Yield

Each year growers are faced with the decision of when to harvest individual blocks of sugarcane throughout the harvest season. This decision influences the yield of the current crop and can affect the yield in the following season. Growers must therefore decide which blocks to harvest early and which to harvest later in the harvest season. Usually, the latest harvested cane is the lowest yielding the following year (the �late harvest� effect). Block productivity data from Tully were used to determine the effects of harvest timing on cane yield of the current and subsequent crop. The results are tabulated to provide a ready reference to these time of harvest effects on the current and future crop in either a single year or over the full crop cycle for the Tully district.

Sugar and coffee: A history of settler agriculture in nineteenth-century Liberia

This dissertation is about commercial agriculture in nineteenth-century Liberia. Based primarily on the archives of the American Colonization Society (founder of Liberia), it examines the impact of environmental and demographic constraints on an agrarian settler society from 1822 to the 1890s. Contrary to the standard interpretation, which linked the poor state of commercial agriculture to the settlers' disdain for cultivation, this dissertation argues that the scarcity of labor and capital impeded the growth of commercial agriculture. The causes of the scarcity were high mortality, low immigration and the poverty of the American “Negroes” who began to settle Liberia in 1822. ^ Emigration to Liberia meant almost certain death and affliction for many immigrants because they encountered a new set of diseases. Mortality was particularly high during the early decades of colonization. From 1822 to 1843, about 48 percent of all immigrants died of various causes, usually within their first year. The bulk of the deaths is attributed to malaria. There was no natural increase in the population for this early period and because American “Negroes” were unenthusiastic about relocation to Liberia, immigration remained sparse throughout the century. Low immigration, combined with the high death rate, deprived the fledgling colony of its potential human resource, especially for the cultivation of labor-intensive crops, like sugar cane and coffee. Moreover, even though females constituted approximately half of the settlers, they seldom performed agricultural labor. ^ The problem of labor was compounded by the scarcity of draft animals. Liberia is in the region where trypanosomiasis occurs. The disease is fatal to large livestock. Therefore, animal-drawn plows, common in the United States, were never successfully transplanted in Liberia. Besides, the dearth of livestock obstructed the development of the sugar industry since many planters depended on oxen-powered mills because they could not afford to buy the more expensive steam engine mills. ^ Finally, nearly half of the immigrants were newly emancipated slaves. Usually these former bondsmen arrived in Liberia penniless. Consequently, they lacked the capital to invest in large-scale plantations. The other categories of immigrants (e.g., those who purchased their freedom), were hardly better off than the emancipated slaves. ^

A New Opportunity to Pulp Bagasse in Australia?

Despite the large quantity of sugarcane grown in Australia, no bagasse is pulped in the country. This is largely because of an established pulp industry based on the abundant native hardwood resources. However, increasing demand for fibre and the limited availability of additional forest areas make bagasse pulping attractive. Issues relating to infrastructure and economics are discussed, and scenarios of acceptable risk identified. It is shown that there should be scope for the production of bleached bagasse pulp in Australia.

A Preliminary Assessment of Aqueous Ethanol Pulping of Bagasse: the Ecopulp Process

SRI has examined the organosolv (organic solvation) pulping of Australian bagasse using technology supplied by Ecopulp. In the process, bagasse is reacted with aqueous ethanol in a digester at elevated temperatures (between 150ºC and 200ºC). The products from the digester are separated using proprietary technology before further processing into a range of saleable products. Test trials were undertaken using two batch digesters; the first capable of pulping about 25 g of wet depithed bagasse and the second, larger samples of about 1.5 kg of wet depithed bagasse. From this study, the unbleached pulp produced from fresh bagasse did not have very good strength properties for the production of corrugated medium for cartons and bleached pulp. In particular, the lignin contents as indicated by the Kappa number for the unbleached pulps are high for making bleached pulp. However, in spite of the high lignin content, it is possible to bleach the pulp to acceptable levels of brightness up to 86.6% ISO. The economics were assessed for three tier pricing (namely low, medium and high price). The economic return for a plant that produces 100 air dry t/d of brownstock pulp is satisfactory for both high and medium pricing levels of pricing. The outcomes from the project justify that work should continue through to either pilot plant or upgraded laboratory facility.

Bagasse Fractionation by the Soda Process

The soda process was the first chemical pulping method and was patented in 1845. Soda pulping led to kraft pulping, which involves the combined use of sodium hydroxide and sodium sulfide. Today, kraft pulping dominates the chemical pulping industry. However, about 10% of the total chemical pulp produced in the world is made using non-wood material, such as bagasse and wheat straw. The soda process is the preferred method of chemical pulping of non-wood materials, because it is considered to be economically viable on a small scale and for bagasse is compatible with sugarcane processing. With recent developments, the soda process can be designed to produce minimal effluent discharge and the fouling of evaporators by silica precipitation. The aim of this work is to produce bagasse fibres suitable for papermaking and allied applications and to produce sulfur-free lignin for use in specialty applications. A preliminary economic analysis of the soda process for producing commodity silica, lignin and pulp for papermaking is presented.