Fertility Investment Research Articles

YIELDFIT: A computer program for determining economic fertilization rates

Fertilizer economics are often omitted or receive very little attention in soil fertility courses. YIELDFIT is a microcomputer program developed to aid soil fertility students in understanding the use of production functions and calculation of maximum economic fertilization rates for a single nutrient source. Routines for fitting Mitscherlich, quadratic, and square root functions are included in the program. The student starts with a set of yield data to which these models are fitted using least squares procedures. Generated equations become yield models for calculation of economic optimum rates. Students can interactively change algebraic functions, prices for crop and fertilizer, and overhead costs. Graphic output allows students to evaluate effects of these changes on gross revenue, net profit, and return on fertilizer investment.

Continuing Response of Pinus radiata to Phosphatic Fertilizers Over Two Rotations

Abstract Considerable growth responses to two differing phosphatic fertilizers (rock phosphate and superphosphate) applied to Pinus radiata (D. Don) were previously reported by the authors (Forest Science 11, 1965). At that time the experimental site had carried two rotations of trees, the first unfertilized. The same site has now been grown through a similar period of time in the third rotation (to first thinning) with no further fertilizer applications. Growth responses, foliage and soil chemical analyses have been compared with those obtained over the first fertilized rotation. Results showed that tree growth responses have been maintained significantly through two fertilized rotations to the present time by the original 1947 fertilization. The bulk of the phosphorus from both sources is still present in the soil surface horizon, that from rock phosphate mainly as calcium phosphate, and from superphosphate mostly in aluminum- and iron-bound forms. Implications for forest management are that where adequate growth responses can be obtained from a single long-lived fertilizer source, the investment in fertilizer becomes a long-term addition to forest site quality. Cost effectiveness has been compared for both rotations in terms of 1983 dollars. Forest Sci. 32:822-829.

Russet Burbank yield response to sprinkler-applied nitrogen fertilizer

Yield response curves were developed for potatoes (Solanum tuberosum cv. Russet Burbank) with sprinkler-applied N fertilizer on a high-frequency schedule. The potatoes were grown on a Quincy sand to loamy sand (mixed, mesic, Xeric Torripsamments) typical of sandy-textured soils of the center-pivot irrigated areas of the Columbia River Basin of Oregon and Washington. These soils require daily irrigation at peak evapotranspiration because of low water-holding capacity. Yields were measured for total quantities of N, ranging from 100 to 665 kg N/ha, applied in small frequent increments as a urea-NH4NO3 solution. Maximum tuber yields ranged from 67 to 85 Mg/ha in 6 experiments over a period of 6 years. Economically optimum yields were obtained at fertilizer rates between 300 and 400 kg N/ha depending on cost-price ratio of N fertilizer and potatoes. Fertilization in this range should optimize tuber yield and quality with fertilizer N efficiency and economic return on fertilizer investment.

Nitrogen Uptake Patterns of Potatoes with High‐Frequency Sprinkler‐Applied N Fertilizer1

AbstractIn order to understand utilization of N by Russet Burbank, a commonly grown indeterminate potato (Solanum tuberosum L.) cultivar, it is necessary to determine the partitioning of N in the plant. Fertilizer N efficiency is closely related to the latter. The objective of this research was to examine differences in N uptake patterns of Russet Burbank potatoes with N applied at excessive, adequate, and deficient levels in daily sprinkler irrigation. The N levels were selected on the basis of statistical significance of yield response to N fertilization. Experiments in 1980 and 1981 were done on a Quincy sand to loamy sand (mixed, mesic, Xeric Torripsamments) typical of coarse‐textured soils used for potato production in the Western United States. Daily mid‐season applications of a urea‐NH4NO3 solution were made for about 10 weeks through solid set sprinklers. Samples of vines and tubers were collected weekly and analyzed for total N. To show partitioning and time changes of vine and tuber N, regression curves were fitted to data for N uptake with time after emergence. Rate of N uptake functions were derived and used to determine N sink dominance by vines or tubers. At fertilizer rates greater than adequate for optimum tuber yield, the excess N showed up as increased N in vines and tubers with vines as the dominant N sink. At adequate and deficient N levels tubers were dominant N sinks, however, the deficient plants did not have a sufficient N supply for optimum yield. A desirable N uptake pattern is associated with the following: (i) A fertilizer N level that is adequate such that tuber yield and economic return on fertilizer investment are optimized which is about 340 kg N/ha for these experiments and (ii) The tubers express N uptake dominance (highest rate) from the start of rapid tuber development causing peak quantity of vine N uptake in the first one‐third to one‐half of the post‐emergent growth period.

Adoption of Agricultural Innovations in Developing Countries: A Survey

This paper reviews various studies which have provided a description and possible explanation to patterns of innovation adoption in the agricultural sector. The survey points out that the tendency of many studies to consider innovation adoption in dichotomous terms (adoption/nonadoption) may not be appropriate in many cases where the actual decisions are defined over a more continuous range. More attention needs to be given to the socio-cultural and institutional environment in area studies so that their interrelation with economic factors affecting adoption can be inferred. The presence of several interrelated innovations is another aspect that needs to be considered more carefully in future research, since a number of simultaneous decisions may be involved. Furthermore, the possibility of regular sequential patterns in adopting components of a new technological package should be specifically addressed in future studies. Finally, the impact of differential adoption rates on land holding distribution merits attention in future research.

Identification of Lower Coastal Plain Sites of Low Soil Fertility

Abstract Analysis of forest survey plot data for 16 coastal counties in North Carolina indicated substantial areas of very low productivity for pine growth were associated with two site types, savannas and pocosins, that are easily identified by aerial photo interpretation. Results indicate that the ready identifiability of such areas provides a rapid method for screening areas for soil test sampling and for making large-scale economic appraisals of sites where fertilizer investments might be worthwhile.

EFFECTS OF FERTILIZERS, SPECIES, AND MATURITY ON YIELDS, ECONOMIC RETURNS, AND NUTRITIVE VALUE OF GRASSES AND LEGUMES GROWN ON A GRAY WOODED SOIL

Samples of hay produced on variously fertilized permanent plots located on a Gray Wooded soil were collected in 1966 and 1967 at two stages of maturity. The composition of the samples was determined by hand-sorting, drying, and weighing. Yields were compared to long-time averages on the plots. Nutritive effects were evaluated by protein analyses and in vitro digestibility studies. Results showed that the nitrogen–phosphorus–sulfur (NPS) + manure fertilizer treatment gave the highest yield, the nitrogen–sulfur (NS) treatment gave the highest return on fertilizer investment, and the NPS treatment was best when both yield and protein were considered. The effects of crop management factors such as time of cutting, weed control, length of rotation, and climatic variation on production of good quality hay were clearly evident.

Optimal Levels of Fertilization Under Risk: The Potential for Corn and Wheat Fertilization Under Alternative Price Policies in Argentina

AbstractBecause economic return from fertilization is stochastic, a precise assessment of the risk in fertilizer investment is critical, especially in less‐developed countries. Using corn and wheat fertilizer response data from the Argentine Pampa, production conditions under which use of fertilizer would be economical are determined. Government protection of an obsolete fertilizer industry, high fertilizer prices, and inadequate tax breaks for users retard development of modern fertilizer technology. Despite current prices, fertilization would be possible on a majority of Argentine farms. Lack of use is attributed to the unavailability to farmers of technical and economic information. Social gains from alternative fertilizer price policies are calculate.