Catch crops in the Argentinean Pampas: a synthesis-analysis on nutrient characteristics and their implications for a sustainable agriculture

Catch crops (CCs) are crops that grow between two cash crops, accumulating nutrients in their biomass and later releasing them through the decomposition of their residues. To our knowledge, no study has compared the nutrient-related traits of different CCs species. This comparison is essential for understanding the possible roles of CCs in agroecosystems and for optimizing adjustments of fertilizer rates. This study aims to: i) synthesize characteristics of the CCs, such as aboveground dry matter accumulation, nutrient [carbon (C), nitrogen (N), sulfur (S), and phosphorus (P)] concentration and accumulation, and C:nutrient ratios, ii) explore factors defining the mentioned characteristics, and iii) discuss their implications on the ecosystem services provided. By analyzing data from 52 studies, (98 site-years) in the Argentinean Pampas, we observed that grasses (excluding ryegrass) accumulated the greatest aboveground dry matter (6.08 ± 0.22 t ha-1, mean ± SE) and C (2.60 ± 0.13 t ha-1), making them suitable for protecting the soil surface from erosion, suppressing weeds, and improving C balances. Conversely, vetch accumulated the highest nutrient content (118 ± 5.3, 15 ± 1.5, and 14 ± 1.2 kg ha-1 for N, S, and P, respectively) with the lowest C:nutrient ratio (means of 15:1, 152:1, and 147:1 for N, S, and P, respectively), making it a suitable choice for recycling nutrients and providing extra N. Mixtures presented intermediate characteristics between the monocultures, allowing a balanced provision of the mentioned ecosystem services. Furthermore, the results showed that dry matter accumulation affected the nutrient-related traits analyzed, and it was related to different factors, such as CCs sowing and termination dates or precipitation. The analysis highlights the importance of selecting CCs species based on the desired ecosystem service and provides valuable information for producers as well as for modeling C balances and nutrient cycling

Analysis of factors controlling maize yield response to hairy vetch and to nitrogen fertilization after hairy vetch

Context or problem: Several agricultural producers around the world are adopting hairy vetch (HV) (Vicia villosa Roth) inclusion in the crop sequence before maize (Zea mays L.). To date, it is not clear which factors control maize yield response to HV and to nitrogen (N) fertilization in HV-maize sequences. Objective or research question: We aimed to i) explore the variability of maize grain yield response to HV and to N fertilization (after HV) and ii) analyze the factors that define the mentioned variability. Methods: We conducted 25 field studies in the southeastern Argentinean Pampas, exploring a wide range of conditions related to HV management and edaphoclimatic properties. We evaluated four treatments resulting from the combination of two preceding conditions, i) HV and ii) bare fallow (BF), and two situations of N fertilization on maize i) with N and ii) without N. Results: We observed that, without N fertilization, maize yield significantly increased by 1846 kg ha−1 due to HV, and the response was significant in 52% of the studies. Low-yield environments exhibited a greater yield response to HV than high-yield environments (2792 vs. 989 kg ha−1). Nitrogen supply from HV was the main factor determining variations in grain yield response to HV, although factors other than N (e.g., water availability, changes in soil physical and biological properties) presented a significant effect (avg. 366 kg ha−1). Specifically, the N supply from HV and soil N availability explained maize yield response to HV. We calibrated and validated a model from these variables that explained 61% of the variability in yield response to HV. We also observed that N fertilization after HV increased maize yield, on average, by 1301 kg ha−1 (significant in 36% of the sites), which was almost half of the response to N fertilization after BF (avg. 2782 kg ha−1, significant in 68% of the sites). Maize yield response to N after HV was explained by both the maize N demand and the N supply from HV. Conclusions: Nitrogen supply from HV and soil N availability defined maize grain yield response to HV. Including HV in crop sequences before maize reduced its fertilizer-N requirement. Maize N demand and N supplied from HV explained the grain yield response to fertilizer-N. Implications or significance: The information and models provided will allow producers to assess the convenience of including HV before maize in the crop sequence and to adjust N fertilization rates, avoiding yield penalties and negative environmental externalities.Fil: Carciochi, Walter Daniel. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Cafaro la Menza, Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Crespo, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Dominguez, Germán. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Rodríguez, María Pía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Reussi Calvo, Nahuel Ignacio. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Wyngaard, Nicolás. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Sainz Rozas, Hernan Rene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Studdert, Guillermo Alberto. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Barbieri, Pablo Andres. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentin

Cover crop species can increase or decrease the fertilizer-nitrogen requirement in maize

Cover crop species and termination date could affect fertilizer-N management and N diagnostic methods traditionally used in bare fallow-maize (Zea mays L.) systems. Our objectives were to (a) assess the impact of cover crop termination date on maize yield and response to fertilizer-N, (b) determine maize yield at varying N rates following different cover crop species and mixtures, and (c) evaluate the chlorophyll meter reading (CMR), grain N concentration (Nc), and grain N nutrition index (NNI) as N diagnostic methods. Experiments were conducted at four sites in the southeastern Argentinean Pampas with maize planted after cover crops. Factors investigated were cover crops with vetch (Vicia villosa Roth), vetch-oat (Avena sativa L.) mixture, or bare fallow; early termination of cover crops or about 3 wk later; and maize fertilizer-N at 0, 50, 100, and 200 kg N ha–1. The minimum N rate that maximized grain yield was higher in vetch-oat mixture (100 kg N ha–1) than in vetch (50 kg N ha–1). Maize yield was not affected by cover crops with 200 kg N ha–1. Late termination dates of vetch-oat mixture reduced maize yield by 15% compared with early termination dates, while there was no effect of vetch termination date. Cover crop termination date did not affect yield response to fertilizer-N. Relative CMR at silking, grain NC, and especially grain NNI at maturity were useful tools to diagnose maize N status and cover crop effect. Cover crop management should be considered to adjust the fertilizer N rate and optimize maize productivity.EEA BalcarceFil: Carciochi, Walter Daniel. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Carciochi, Walter Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Massigoge Ignacio. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Massigoge Ignacio. Kansas State University. Department of Agronomy; Estados Unidos.Fil: Lapaz Olveira, A. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Reussi Calvo, Nahuel Ignacio. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Reussi Calvo, Nahuel Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Reussi Calvo, Nahuel Ignacio. Kansas State University. Department of Agronomy; Estados Unidos.Fil: Cafaro La Menza, Francisco. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Sainz Rozas, Hernán René. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina.Fil: Sainz Rozas, Hernán René. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Sainz Rozas, Hernán René. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Barbieri, Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina.Fil: Barbieri, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Di Napoli, M. Asociación Argentina de Consorcios Regionales de Experimentación Agrícola; Argentina.Fil: Gonzalez Montaner, J. Asociación Argentina de Consorcios Regionales de Experimentación Agrícola; Argentina.Fil: Ciampitti, Ignacio A. Kansas State University. Department of Agronomy; Estados Unidos