A pluriannual experiment was conducted at Verano (PC) to measure the yield response to N and P of irrigated grassland. A split-plot experimental design with five N treatments (100, 150, 200, 400, and 800 kg/ha N per year) and three P sub-treatments (0, 100, and 200 kg/ha P2O5 per year) was executed between 1975 and 1981, with levels of hay (dry matter) production far above those achieved with traditional applications. A Liebig response function, embodying the famous law of minimum, was chosen to represent the response relation between hay production and fertilizers. The N response is satisfactorily represented by a linear and plateau (LRP) function. The P response was estimated by means of a Mitscherlich exponential function and a fertility carryover equation which relates the quantity of available P in the soil at time t to the same quantity at t0 the accumulated additions of P and the total amounts removed by the crop. Such a Liebig response function seems to fit the data very well. The optimal P fertilizer application is computed by taking into account the price ratio, as usual, but also the amount of available P in the soil. The optimal amount of N, on the contrary, is independent of the price ratios and corresponds to the knot in the linear spline.

Funzione di risposta e fertilità residua dei prati stabili nel piacentino / P., Paris; Q., Paris; Lalla, Michele; C., Gavazzi. - In: RIVISTA DI AGRONOMIA. - ISSN 0035-6034. - STAMPA. - 17 (4):(1983), pp. 429-438.

Funzione di risposta e fertilità residua dei prati stabili nel piacentino

LALLA, Michele;
1983

Abstract

A pluriannual experiment was conducted at Verano (PC) to measure the yield response to N and P of irrigated grassland. A split-plot experimental design with five N treatments (100, 150, 200, 400, and 800 kg/ha N per year) and three P sub-treatments (0, 100, and 200 kg/ha P2O5 per year) was executed between 1975 and 1981, with levels of hay (dry matter) production far above those achieved with traditional applications. A Liebig response function, embodying the famous law of minimum, was chosen to represent the response relation between hay production and fertilizers. The N response is satisfactorily represented by a linear and plateau (LRP) function. The P response was estimated by means of a Mitscherlich exponential function and a fertility carryover equation which relates the quantity of available P in the soil at time t to the same quantity at t0 the accumulated additions of P and the total amounts removed by the crop. Such a Liebig response function seems to fit the data very well. The optimal P fertilizer application is computed by taking into account the price ratio, as usual, but also the amount of available P in the soil. The optimal amount of N, on the contrary, is independent of the price ratios and corresponds to the knot in the linear spline.
1983
17 (4)
429
438
Funzione di risposta e fertilità residua dei prati stabili nel piacentino / P., Paris; Q., Paris; Lalla, Michele; C., Gavazzi. - In: RIVISTA DI AGRONOMIA. - ISSN 0035-6034. - STAMPA. - 17 (4):(1983), pp. 429-438.
P., Paris; Q., Paris; Lalla, Michele; C., Gavazzi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/628180
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