Journal of Production Agriculture 

About: Journal of Production Agriculture is an academic journal. The journal publishes majorly in the area(s): Loam & Forage. It has an ISSN identifier of 0890-8524. Over the lifetime, 1207 publications have been published receiving 25279 citations.

The Concept and Need for a Phosphorus Assessment Tool

Abstract: Nonpoint sources of P leaving the agricultural landscape can cause eutrophication of surface water and the associated growth of undesirable aquatic plants. USDA is developing an indexing procedure for identifying soils, landforms, and management practices that could have unfavorable impacts on water bodies because of P movement. This indexing procedure uses the characteristic of the field site, including soil erosion rates, runoff, available P soil test levels, and fertilizer and organic P application rates and methods to assess the degree of vulnerability of P movement from the site. A weighting procedure has been developed to include the various contributions each site characteristic may have. A summation of the products of the weighted site characteristic yields a site vulnerability rating [...]

Use of a Chlorophyll Meter to Monitor Nitrogen Status and Schedule Fertigation for Corn

Abstract: The SPAD 502 chlorophyll meter 1 (Minolta Camera Co., Osaka, Japan) is a new instrument that has been introduced as a tool to improve N management. This study was conducted to evaluate the ability of the chlorophyll meter to detect plant N deficiencies in corn (Zea mays L.) by identifying when it would be appropriate to supply N fertilizer in irrigation water. Nitrogen response studies were conducted on five irrigated sites in central Nebraska in 1991. Crop N status was monitored during the growing season and additional N was added to simulate fertigation when apparent N deficiencies were detected with the meter. Changes in N status over the season were determined relative to an adequately fertilized in-field reference plot. Earlyseason (V6) N deficiencies were poorly correlated with yield because factors such as nitrate leaching, organic matter mineralization, and nitrate present in irrigation water modified the crop N supply during the growing season. Nitrogen deficiencies detected late (R4-R5) in the season were more highly correlated with yield than early season N stresses. Treatments that started with adequate fertilizer and then became deficient were corrected without yield loss. Young plants in a deficient state could not be corrected to full yield potential. Chlorophyll meters can be a valuable tool for N management of irrigated corn production when used to assess crop N status in the irrigated Great Plains

Phosphorus Movement in the Landscape

Abstract: Phosphorus movement in runoff often promotes algal growth in lakes. Thus, agricultural soils and management practices that enhance the potential for P movement must be identified. The main factors controlling P movement are transport (runoff and erosion potential) and source factors (surface soil P and method, rate, and timing of fertilizer and animal manure applications). Implementation of management that minimizes runoff and erosion will reduce P transport in runoff, although total algal availability can increase. The continued application of P has increased surface soil test P contents in excess of levels sufficient for optimum crop yields. Although increases in soil P have been related to P enrichment of runoff in plot and watershed studies, information for given management systems still is needed to reliably quantify critical soil P levels above which excessive P enrichment of runoff will occur [...]