Soil carbon and nitrogen response to 25 annual cattle manure applications

Improving manure management to benefit both agricultural production and the environment requires a thorough understanding of the long‐term effects of applied manure on soil properties. This paper examines the effect of 25 annual solid cattle manure applications on soil organic carbon (OC), total N (TN), and KCl‐extractable NO3‐N and NH4‐N under both non‐irrigated and irrigated conditions. After 25 annual manure applications, OC and TN contents increased significantly with the rate of manure application at the top two sampling depths (0–15 cm and 15–30 cm), and the increases were not affected by the irrigation treatment. The NO3 content increased at all sampling depths with greater increases observed under non‐irrigated conditions, while NH4 content was not affected by manure application rates or the irrigation treatment. The changes in OC and TN at the surface (0–15 cm) and 15–30 cm depth were dependent on the cumulative weight of manure added over the years. The relationships between cumulative manure OC added and soil OC content and between cumulative manure TN added and soil TN content were linear and not affected by the irrigation treatment. For every ton of manure OC added, soil OC increased by 0.181 g kg–1 in the topsoil (0–15 cm). Similarly, for every ton of manure TN added, surface soil TN increased by 0.192 g kg–1. The linear relationship between manure C added and soil C content suggests that the soil had a high capacity for short‐term C sequestration. However, the total amount of NO3‐N in the soil profile (0–150 cm) was affected by both the manure application rates and the irrigation treatment. A large amount of NO3 accumulated in the soil, especially under non‐irrigated conditions. The extremely high level of NO3 in the soil increases the potential risk of surface and groundwater pollution and losses to atmosphere as N2O. Reaktion des Boden‐C und ‐N auf Düngung mit Rindermist über 25 Jahre Die Verbesserung des Stalldung‐Managements zur Unterstützung der umweltgerechten landwirtschaftlichen Produktion erfordert ein grundlegendes Verständnis der Langzeiteffekte der zugeführten Dünger auf die Bodeneigenschaften. In dieser Studie wurden die Auswirkungen einer 25‐jährigen Zufuhr von Rinder‐Festmist auf die Gehalte an organischem Kohlenstoff (OC), Gesamt‐N (TN) und KCl‐extrahierbarem NO3‐N and NH4‐N bei Bewirtschaftung ohne und mit Beregnung untersucht. Nach 25 Jahren waren die Gehalte an OC und TN in den Bodenschichten 0–15 cm und 15–30 cm entsprech