Does Information Matter? Assessing the Role of Information and Prices in the Nitrogen Fertilizer Management Decision

This article investigates the impact of agronomic, environmental, and price information on the management decision of nitrogen fertilizer. Because excessive nitrogen originating from agricultural production activities can cause environmental degradation, understanding how information influences the nutrient application decision on the field is important for developing strategies for nitrogen load mitigation. I investigate the value farmers place on information about N management they receive from several sources. In particular, I evaluate how farmers use information from soil N-tests to make decisions about the rate of N to apply to the field. My results show that soil N-testing can be an effective management practices for reducing excess N applications. I find farmers who use a soil test reduce their use of commercial N by up to 14 lbs/ac relative to non-testers. I also find new evidence that rising fertilizer prices encourage farmers to manage N more carefully. I estimate a price elasticity of demand of between -0.6 and -1.29. I also show prices play a role in other forms of N management behavior, including application method and timing.Nitrogen Fertilizer Application, Soil N-testing, Agronomic Information, Best Management Practices, Nonpoint Source Pollution, Demand and Price Analysis, Environmental Economics and Policy, Q24, Q28,

Revised estimation of 550-km times 550-km mean gravity anomalies

The calculation of 550-km x 550-km mean gravity anomalies from 1 degree x 1 degree mean free-air gravimetry data is discussed. The block estimate procedure developed by Kaula is used to obtain 1,504 of the 1,654 possible mean block anomalies. The estimated block anomalies calculated from 1 deg x 1 deg mean anomalies referred to the reference ellipsoid and from 1 degree x 1 degree mean anomalies referred to a 24th-degree-and-order field are compared

Revision of geodetic parameters

Laser data from nine satellites and 12 stations are combined with surface-gravity data to obtain spherical harmonics representing the geopotential complete through degree and order 18. This laser-data-only solution provides a reasonable improvement to the gravity field

Robot docking using mixtures of Gaussians

This paper applies the Mixture of Gaussians probabilistic model, combined with Expectation Maximization optimization to the task of summarizing three dimensionals range data for the mobile robot. This provides a flexible way of dealing with uncertainties in sensor information, and allows the introduction of prior knowledge into low-level perception modules. Problems with the basic approach were solved in several ways: the mixture of Gaussians was reparameterized to reflect the types of objects expected in the scene, and priors on model parameters were included in the optimization process. Both approaches force the optimization to find 'interesting' objects, given the sensor and object characteristics. A higher level classifier was used to interpret the results provided by the model, and to reject spurious solutions

Anomalous enhancement of a penguin hadronic matrix element in B->K eta'

We estimate the density matrix element for the pi^0, eta and eta' production from the vacuum in the large-N_c limit. As a consequence, we find that the QCD axial anomaly leads to highly non-trivial corrections to the usual flavour SU(3) relations between B^0-> K^0 pi^0, B^0-> K^0 eta and B^0-> K^0 eta' decay amplitudes. These corrections may explain why the B-> K eta' branching ratio is about six times larger than the B-> K pi one.Comment: 5 pages, 1 figur