<p>Oil palm (<i>Elaeis guineensis</i> Jacq.) is the world’s leading source of vegetable oil and an important driver of rural economic activity in Southeast Asia, West Africa, and the equatorial region of Latin America. In the Llanos region of Colombia, palm oil production is additionally an important vehicle for legal employment and social stability in a region deeply affected by the country’s longstanding and recently-concluded armed conflict. The economic viability of palm oil production is thus of great interest to both those directly employed in the industry and to the larger society around them, and yet oil palm remains a relatively understudied cropping system.</p> <p>Spending on fertilizer is one of the largest costs in palm oil production, and plantations face considerable pressure to apply fertilizer as efficiently as possible in order to maintain the profitability of their operations. However, developing strategies for optimizing fertilizer applications in oil palm can be considerably challenging given the particular characteristics of palm oil production systems. Oil palm has a typical life-cycle of 25 years, with harvesting done manually approximately every fifteen days for the duration of the palms productive life-cycle. The morphology of oil palm’s reproductive system makes it possible for environmental changes to affect yield in irregular ways, with the same soil or climate-related stressors having the potential to affect yields either immediately or multiple years after the event. It can therefore be difficult for plantations to link changes in yield patterns to individual management changes or environmental factors. Additionally, since unlike all other major oilseeds oil palms must be harvested manually, plantation managers do not have access to the kind of detailed yield data made possible by mechanized harvesting equipment, but must rely on much more irregular and coarser-resolution information to examine yield variability within plantations. Understanding how the particular soil conditions and fertilizer management history of an individual oil palm plantation drive variability in yields requires employing innovative approaches to maximize the insights to be learned from the available data. </p> <p> For this study, we worked with a 5,220 hectare oil palm plantation in the Colombian Llanos, in the municipality of Villanueva, Casanare. Despite uniform fertilizer applications and management practices, along with uniform climatic conditions within the plantation, significant yield variability existed within the plantation, with plantation managers initially unable to determine the underlying causes. We proposed and evaluated a methodology for using digital terrain and soil mapping for generating continuous soil data within an oil palm production system, based on Functional Soil Mapping (FSM) methods using the SRTM Global Digital Elevation model and geo-referenced soil sampling, with the goal of identifying soil physical, chemical and hydrological properties that could be directly linked to different yield responses to fertilizer application at the field scale. Furthermore, the economic implications for the plantation of infield variability in yield response to fertilizer arising from variation in soil properties were examined. </p> <p>The perennial nature and particularities in reproductive morphology of oil palm, including an approximately 8-10 year growth period before mature yields are reached, mean that developing site-specific yield response curves to different nutrient application levels in oil palm requires extensive time and resources. The PORIM model, developed by the Malaysian Palm Oil Board (MPOB) across multiple decades of extensive and continuous field testing, is one of the most commonly used methods by which plantations can estimate yield response at different levels of fertilizer application. Traditionally, the PORIM model is run by using site-specific low-resolution vector-layer soil analysis to adjust various parameters in multiple equation systems developed using statistical methods and many decades worth of field tests by the MPOB. In this study, the PORIM model is used as the basis for a methodology to employ a precision approach to fertilizer management in oil palm using high-resolution raster-layer soil property maps and a constrained-optimization model programmed in the General Algebraic Modeling System (GAMS). </p>

The influence of genetic variability on the response of the five rice varieties, Cica, Starbonett, Lemont, Bluebonett X IR 43, and IR43, to applied zince at 0, 10, 20 and 40 kg Zn ha^-1 under varying cellulose and water management conditions was studied in a greenhouse experiment. Typical zinc deficiency symptoms, varying in intensity among varieties, were nted, especially in the zero applied zinc treatments. Zinc deficiency symptoms were characterised by blanching at the base of the emerging leaves and rusty brown discolouration in the older leaves.

The influence of genetic variability on the response of the five rice varieties, Cica, Starbonett, Lemont, Bluebonett X IR 43, and IR43, to applied zince at 0, 10, 20 and 40 kg Zn ha^-1 under varying cellulose and water management conditions was studied in a greenhouse experiment. Typical zinc deficiency symptoms, varying in intensity among varieties, were nted, especially in the zero applied zinc treatments. Zinc deficiency symptoms were characterised by blanching at the base of the emerging leaves and rusty brown discolouration in the older leaves.

<p> Brown patch (caused by various <em>Rhizoctonia </em>and <em>Rhizoctonia-</em>like species) is one of the major summer diseases of tall fescue [<em>Schedonorus arundinaceus</em> (Schreb.) Dumort., nom. cons.]. Fungicides are available to suppress brown patch; however, there is increasing interest to reduce lawn pesticide inputs. Excessive summer nitrogen (N) applications and extended periods of leaf wetness have been suggested to enhance brown patch. Five projects were conducted from 2020 to 2022 to evaluate individual and various combinations of cultural management practices to improve brown patch management strategies through reducing chemical inputs and promoting environmentally sound integrated pest management (IPM) practices. Brown patch host resistance of 15 tall fescue cultivars was evaluated in a controlled environment study and various morphological characteristics were correlated to brown patch severity. A 45% reduction in brown patch was observed with a resistant cultivar, and cultivars with faster growth rates, wider sheath widths and shorter sheath length correlated with reduced brown patch resistance. A field study evaluated five cultivars fertilized with urea-N from April to July, totaling 73.5 or 245.0 kg N ha^-1. A resistant cultivar had the greatest influence on reducing disease, and N-rate generally did not influence disease severity. Differences in seasonal brown patch was compared in a three-year field study for various natural organic fertilizers. Feather-bone meal and soybean meal-based products decreased disease compared to non-fertilized turf. Chemical suppression of leaf-wetness was studied using different surfactant chemistries applied on a 14 to 21-d application frequency and some chemistries reduced disease. When evaluating the various interactions of cultivar, N rate, and surfactant compared to a granular fungicide, the greatest impact was achieved when planting a resistant cultivar, reducing disease severity by 68%. Additionally, the combination of a resistant cultivar and application of a surfactant had the same seasonal brown patch compared to a susceptible cultivar with fungicide applications during year two of evaluation. In summary, these studies demonstrate significant reductions in brown patch can be achieved when utilizing the aforesaid best management practices which can substantially reduce the need for frequent lawn fungicides.  </p>