Piero Iori

Contact pressures and the impact of farm equipment on Latosol with the presence and absence of sugarcane straw

High contact pressures applied to soil result in a greater degree of compaction, in addition to promoting other negative effects. The objective of this study was to quantify contact areas by using different methodologies, and pressures of farm equipment employed in production activity and evaluate structural changes caused in a Red Latosol with the presence and absence of straw cover. The design was completely randomized in a factorial scheme of type 4 (tire on front axle, tire on rear axle, tire on a sugarcane wagon and metallic track of sugar cane Harvester) x 2 (presence and absence of straw). The contact area (CA) of the run was obtained by three procedures: analytical measure of the area of an ellipse (CA1); digital measurement of area of an ellipse (CA2); and measurement of real contact area (RCA), with digital resources. The contact pressure was calculated from the ratio of mass of each machines axle and the contact area of the run. The contact area obtained according to the procedure of the ellipse (CA1 and CA2) is overrated when compared to actual area obtained digitally (RCA). The straw reduces the contact pressure in the soil, due to the deep tire treads and consequently, increased contact area. Areas where the traffic of the machines occurred with soil covered with the presence of straw showed reduced soil resistance to penetration, cone index and pre-consolidation pressure, confirming that the increased contact area produced by straw reduced the pressure applied and the compression power dissipated in the soil.High contact pressures applied to soil result in a greater degree of compaction, in addition to promoting other negative effects. The objective of this study was to quantify contact areas by using different methodologies, and pressures of farm equipment employed in production activity and evaluate structural changes caused in a Red Latosol with the presence and absence of straw cover. The design was completely randomized in a factorial scheme of type 4 (tire on front axle, tire on rear axle, tire on a sugarcane wagon and metallic track of sugar cane Harvester) x 2 (presence and absence of straw). The contact area (CA) of the run was obtained by three procedures: analytical measure of the area of an ellipse (CA1); digital measurement of area of an ellipse (CA2); and measurement of real contact area (RCA), with digital resources. The contact pressure was calculated from the ratio of mass of each machine’s axle and the contact area of the run. The contact area obtained according to the procedure of the ellipse (CA1 and CA2) is overrated when compared to actual area obtained digitally (RCA). The straw reduces the contact pressure in the soil, due to the deep tire treads and consequently, increased contact area. Areas where the traffic of the machines occurred with soil covered with the presence of straw showed reduced soil resistance to penetration, cone index and pre-consolidation pressure, confirming that the increased contact area produced by straw reduced the pressure applied and the compression power dissipated in the soil.

Influence of field slope and coffee plantation age on the physical properties of a red-yellow Latosol

In modern agriculture, several factors cause changes in the soil physical properties. The time of establishment of a crop (plantation age) and the slope are examples of factors that moderate the impact of mechanized operations on the soil structure. The objective of this study was to analyze the effect of machinery traffic on the physical properties of a Red-Yellow Latosol under coffee plantations with different ages (2, 7, 18, and 33 years) and slope positions (3, 9 and 15 %). Samples were collected from three positions between coffee rows (lower wheel track, inter-row and upper wheel track) and at two depths (surface layer and sub-surface). Changes in the total porosity, macroporosity, microporosity, organic matter, bulk density, and aggregate stability were investigated. Our results showed that the slope influenced the organic matter content, microporosity and aggregate stability. The soil samples under the inter-row were minimally damaged in their structure, compared to those from under the lower and upper wheel track, while the structure was better preserved under the lower than the upper track. The time since the establishment of the crop, i.e., the plantation age, was the main factor determining the extent of structural degradation in the coffee plantation.

Changes in contents of macronutrients in a Oxisol grown with cane sugar levels under applicable irrigation and nitrogen.

Nos diferentes ambientes agricolas, a produtividade dos canaviais brasileiros tem sido limitada, principalmente, por restricoes hidricas e pela disponibilidade de nutrientes dos solos. O objetivo deste estudo foi avaliar as alteracoes nos teores de macronutrientes de um solo cultivado com cana-de-acucar irrigada com diferentes niveis de reposicao hidrica, com e sem fornecimento de nitrogenio, no ciclo da cana-planta. O experimento foi conduzido em area experimental do Instituto Federal Goiano - Campus Rio Verde, GO, em um Latossolo Vermelho distroferrico. A variedade cultivada foi RB 85-5453, irrigada com cinco niveis de reposicao hidrica (100, 75, 50, 25 e 0%) por gotejamento subsuperficial, combinados com e sem aplicacao de nitrogenio (0 e 100 kg ha-1 de N) parcelada via fertirrigacao. Foi avaliada a produtividade de colmos da cana-de-acucar e a analise quimica do solo em dois periodos, ao final do parcelamento da adubacao e proximo a colheita, em duas camadas do solo, superficial (0 a 30 cm) e subsuperficial (30 a 60 cm). A reposicao hidrica com o fornecimento de nitrogenio alterou os teores de macronutrientes do solo ao final do periodo de parcelamento da adubacao via irrigacao por gotejamento subsuperficial. A reposicao hidrica de 100%, combinado com a adubacao nitrogenada proporcionou as maiores produtividades de cana-de-acucar. Os tratamentos que receberam nitrogenio e 100% de reposicao hidrica apresentaram menores teores no solo de nitrogenio, fosforo, calcio e enxofre ao final do ciclo, devido a maior absorcao pelas plantas de cana-de-acucar.