Attribution of crop yield responses to application of organic amendments: A critical review

Abstract

In floriculture, plant residues represent 90% of the total solid residues of the production process. It is important to look for alternatives of waste management, in order to be used;An alternative is composting. The objective of this investigation was to evaluate in 4 times with intervals of 11 weeks, the effect of the use of flower compost on some physical, chemical and biological properties of a soil cultivated with sunflower (Helianthus annuus) in greenhouse. The compost three types used: 100% from dianthus, 100% from sunflower and mixed residues (sunflower-dianthus), which were incorporated into the soil at doses of 8, 12 and 16 Kg / m2 and the control. The characterization and composition of the compost were determined and the chemical properties (pH, Effective Cation Exchange Capacity (CICE), Organic Carbon (CO), phosphorus, nitrogen and sulfur), physical (bulk density, structural stability, porosity and Moisture retention) and biological (Colony Forming Units (CFU) of phosphate solubilizing bacteria, nitrogen fixers and respiration) of the soil and for sunflower cultivation, production was quantified and quality grades were identified. In the results obtained in this investigation, dianthus, sunflower and mixed compost obtained a C / N ratio of 11.4; 13.1 and 11.7 respectively and without the presence of pathogens (Erwinia sp. And Pseudomonas sp.). In terms of physical properties, the apparent density decreased with respect to the initial value (1.14 g / cm3) of 17% and 25% in sunflower and dianthus at doses of 16 kg / m2 respectively. The porosity percentage increased with respect to the initial value (53.9%) of 8.1% and 10.5% in sunflower and mixed at doses of 16 kg / m2 respectively; while the structural stability and humidity retention did not present statistical differences with respect to the control. In chemical properties, the pH increased with respect to the initial value (6.7) by 0.62 and 0.69 in sunflower and dianthus at doses of 16 kg / m2 respectively. In the CICE, it increased with respect to the initial value (19.4 cmol / kg) 7.3 and 10.8 cmol / kg in sunflower and mixed at doses of 12 kg / m2 and 16 kg / m2 respectively. In CO it increased with respect to the initial value (2.44%) 2.33% in mixed at a dose of 16 kg / m2. In N, P and S there were no differences with respect to the control.In biological properties, respiration did not show statistical differences with respect to the control, in the CFU of phosphate-solubilizing bacteria, at time 4, the dose of 16 kg / m2 showed values of 3.5 X 106, 2.24 X 106, 2.29 X 106 CFU / g soil for mixed, dianthus and sunflower respectively, being greater than the control (0.64 X 106 CFU / g soil); In the CFU XII Efecto de la adición de compost de flores sobre algunas propiedades químicas, físicas y biológicas del suelo of nitrogen fixers, the highest values were recorded in dianthus the dose of 12 Kg / m2(1,189 x 107 CFU / g soil), sunflower the dose of 12 Kg / m2 (9,194 x 106 CFU / g soil), mixed the dose of 16 Kg / m2 (3,025 x 107 CFU / g soil) which...

Direct evidence using a controlled greenhouse study for threshold effects of soil organic matter on crop growth

“…a), the same rates of key nutrients should be provided by both the unfertilized and fertilized soils (Celestina et al. ). We did not explicitly control for this; however, our data show that SOM may be able to substitute for mineral N fertilizer in some cases depending on the SOM concentration and whether or not the soils were irrigated.…”

Comparative Performance of Organic Fertilizers in Maize (Zea mays L.) Growth, Yield, and Economic Results

“…The non-significance in maize yields (cob and grain) between organic amendments and DAP in this study may be attributed to the same Nitrogen fertilizer application rate used (50 kg N ha −1 ). Studies have shown that, when organic and inorganic fertilizers are applied at the same rates especially in terms of macronutrients (N, P, and K), similar effects in crop yields are obtained [55][56][57]. Since P and K application rates for the fertilizer treatments differed, no significant differences in maize yields were observed.…”

“…In these studies, high application rates of organic amendments (>15 t ha −1 ) were used. However, according to Celestina et al [55], although high organic amendment rates will eventually ensure high productivity gains, these gains are not necessarily economical. In addition, these high rates can lead to increased greenhouse gas emissions, higher losses to runoff, and reduced nutrient use efficiency.…”

Potential Benefits and Risks for Soil Health Derived From the Use of Organic Amendments in Agriculture

“…Within this circular economy paradigm, the reutilization of organic waste and by-products as soil amendments is gaining much interest, since it poses a realistic, cost-effective, and environmentally sound alternative to landfill disposal (the least preferred option for waste management) [22]. Organic amendments, such as composts, animal manures, slurries, crop residues, digestates from the anaerobic treatment of waste, biosolids, etc., are extensively applied to agricultural soil as fertilizers [23,24] or, alternatively, as amendments in soil remediation and reclamation initiatives [25][26][27][28]. Biofertilizers, defined as "mixtures of selected beneficial microorganisms and/or other organic substances (plant growth hormones, vitamins, etc.)…”