Donato Ferri

Compost Organic Amendments in Fodder Crops: Effects on Yield, Nitrogen Utilization and Soil Characteristics

Agronomic value and environmental impact of two composts were evaluated in a three-year field experiment (2002, 2003 and 2004) on alfalfa and cocksfoot in Southern Italy. The effects of Municipal Solid Waste compost (MSW), Olive Pomace Compost (OPC), mineral fertilizer (Min) (phosphorus as 75 kg ha−1 for alfalfa and nitrogen as 50 kg ha−1 for cocksfoot) and an unfertilized treatment (Contr) were compared on crop yield, soil characteristics and environment impact. During the cropping cycles, fresh and dry weights, plant nitrogen status (leaves SPAD readings and petiole nitrate content) and plant total N content were determined for calculating the protein content and the plant N uptake. Moreover, at the beginning and the end of the research, chemical soil characteristics and heavy metal levels were also determined. The results indicated that in cocksfoot fertilized with MSW and OPC composts, the mean cumulative dry weight increased by 20.85 and 16.51%, respectively compared to the control, but it was significantly lower than Min treatment. In the alfalfa crop, the mean cumulative dry weight of Control, MSW and OPC treatments were very similar and lower than mineral fertilizer (−7.86, −7.09 and −10.31%, respectively). At the end of the experiment, (2004) the soil total N increased significantly in alfalfa (from 1.32 to 1.45 g kg−1) while no significant difference was found for the cocksfoot. After three years of compost application, the total soil organic carbon increased significantly in both crops (23.98% for cocksfoot, and 43.17% for alfalfa in respect to the control), indicating that MSW and OPC amendments positively affected the organic matter. Furthermore, total organic carbon (in both crops) and humified organic carbon (in alfalfa) were significantly lower in the Contr treatment than on the MSW and OPC treatments.

MSW Compost Application on Tomato Crops in Mediterranean Conditions: Effects on Agronomic Performance and Nitrogen Utilization

A two-year field experiment (2001 and 2003) was carried out in a Mediterranean environment to study the effects of municipal solid waste (MSW) compost application compared with mineral nitrogen (N) fertilization on the agronomic performance and N utilization of a tomato crop, in rotation with durum wheat. The research was conducted in the south of Italy where five N treatments and two soil tillage depths (40-45 cm and 10-15 cm) were compared. The N treatments were: MSW compost at 140 kg ha−1 (Ncom); mineral N fertilizer at 140 kg ha−1 (Nmin); MSW compost combined with mineral N fertilizer (Nmix) (70 kg ha−1 as organic N plus 70 kg ha−1 as mineral N); mineral N fertilizer at 70 kg ha−1 combined with two applications of foliar fertilizer (Nfito) (3 kg ha−1 as hydrolyzed proteins), and an untreated control (Contr). During cropping cycles, growth parameters and plant N status (SPAD readings and petiole nitrate content) were determined; at harvest the marketable, overripe, green fruit, total yield, yield components, quality performance, total and fruit N uptake, and N efficiency were recorded. In addition, at the beginning and at the end of the two-year experiment, soil chemical characteristics and mineral N was measured, allowing for the calculation of the mineral N deficit in the soil. The results of this research indicate that the application of MSW compost to tomato plants can serve as a N source in Mediterranean conditions, especially when MSW compost is combined with mineral N fertilizer and deeper soil tillage is applied. In fact, deeper soil tillage increased total yield 7.0 t ha−1 compared to surface tillage, whereas soil amended with MSW compost increased total yield compared to the untreated control by approximately 6.4% when used alone and 11.1% when combined with mineral N fertilizer. Nitrogen utilization parameters and Harvest Index varied significantly across years and N treatments. Petiole nitrate content and SPAD readings did not vary between Nmin and Nmix treatments, but they were significantly different from the untreated control. This indicates that plant N status was an effective tool to monitor N supply. After the two-year experiment, the Nmix treatment was statistically not significant in total yield (86.1 and 88.2 t ha−1, respectively), marketable yield (66.9 and 67.7 t ha−1) and quality compared to the Nmin treatment. Furthermore, the Nmix treatment ensured the least N deficit in the soil, indicating that MSW applications were effectively used as alternative organic supplements. Finally, the results indicated a positive effect of MSW application on organic carbon content in the soil and did not show any significant increase of the heavy metals at the end of the two-year experiment.

Nitrogen Application in Winter Wheat Grown in Mediterranean Conditions: Effects on Nitrogen Uptake, Utilization Efficiency, and Soil Nitrogen Deficit

ABSTRACT Nitrogen (N) is one of the most growth restricting nutrients in cereal grain and represents one of the highest input costs in agricultural systems; therefore, environmental and economic considerations require the effective use of N fertilizer in plant production. This study was conducted for three years to better understand wheat plant response to optimize N fertilizer and how to reduce the risk of ground water pollution. Two of the most important durum wheat cultivars in Southern Italy and four N fertilization levels (0, 60, 120, and 180 kg N ha− 1, indicated as N0, N60, N120, and N180, respectively) were compared in this experiment. During plant growth, fresh and dry matter, plant nutritional state (SPAD readings and stem nitrate content), and N uptake were determined. At harvest, plant N content, N uptake, grain yield, yield components and quality were determined, allowing the calculation of the pre- and postanthesis N uptake and the N utilization efficiency indices. Furthermore, at the beginning and at the end of each year, soil mineral N was measured to calculate mineral N deficit in the soil. The results indicated that the treatment with 120 kg N ha− 1 of fertilizer ensures a good balance between yield and N utilization. In fact, N180 and N120 showed similar yield (3.01 and 3.07 t ha− 1, respectively) and protein content (13.7 and 13.5 %). Meanwhile, throughout the three-year experiment, N180 presented the highest final mineral N content in the soil at the end of the cropping cycles, increasing the amount of N available for leaching. The N120 treatment showed the same values of N utilization indices as compared to N180, indicating that further doses of N fertilizer did not increase wheat N utilization. Plant N status shows that it is possible to modify the N fertilization to reach its optimum level during plant growth, in accordance with variable weather conditions, and consequently the plants requirements. The mean treatments of the preanthesis N uptake were about 67.5% of the total N uptake, and it was significantly and positively correlated with wheat yield. On the contrary, the postanthesis N uptake showed positive correlation with grain protein content, confirming the importance of late N supply in grains quality. The variation of weather conditions affected winter wheat yield, quality, N utilization and plant N status, but any difference throughout years was found between N180 and N120, confirming that higher N rate did not influence wheat growth, yield, and N uptake.

Anaerobic Digestate and On-Farm Compost Application: Effects on Lettuce (Lactuca sativa L.) Crop Production and Soil Properties

A three-year field experiment was conducted in a Mediterranean environment on lettuce to study the production, characteristics and possible use of different amendments as substitution for nitrogen mineral fertilizers. The effects on soil dynamics were also investigated. The following treatments supplying 140 kg N ha−1 were compared: Stabilized anaerobic digestate from wine distillery wastewater (SAD); Non-stabilized organic material from wine distillery wastewater (NSAD); Olive pomace compost (OPC); Mineral N fertilizer (MIN); Commercial organic fertilizer (CORG). These treatments were compared with an unfertilized control (CONTR). No significant reduction occurred with SAD as compared to MIN, but its application significantly increased marketable yield in all experimental years compared to the unfertilized control. Furthermore, SAD treatment reached the highest marketable yield with an increase of 52.9% compared to CONTR in the year characterized by high unevenly rainfall distribution. Even with low absolute values, the application of mineral fertilizer not only had the highest level of nitrate in the leaves but also determined higher value of soil mineral N compared to by-products treatments, thereby increasing pollution risks. The NSAD and the OPC treatments had significantly lower biomass and marketable yield than MIN and presented the highest soil N mineral deficit. As a consequence, the choice and the production of the more appropriate agroindustrial by-product (in our research SAD treatment) is crucial to ensure lettuce yield and the sustainability of agro-ecosystem.

Potential Use of Olive Mill Wastewater as Amendment: Crops Yield and Soil Properties Assessment

The traditional olive oil extraction process generates a large amount of liquid by-product that could be recycled as an organic fertilizer. The aim of this 3-year field experiment was to assess the effects of olive mill wastewater (OMWW) application on yields of ryegrass, proteic pea, and clover crops and on soil properties. The following treatments were compared: OMWW at 80 m3 ha−1 (80_OMWW), OMWW at 120 m3 ha−1 (120_OMWW), and an unfertilized control (Contr). The yields of ryegrass increased 40% and 41.6% compared to Contr, for 80_OMWW and 120_OMWW, respectively, while a significant enhancement was found at the lowest level of OMWW in proteic pea (27.0% increase). Clover showed a species-specific sensitiveness, but the OMWW applications increased the protein content 26.3% and 28.7% for 80_OMWW and 120_OMWW, respectively, in comparison with Contr. The OMWW rates also enhanced the total organic content in the soil compared to the unfertilized control. At the end of the 3-year experiment, total extracted carbon and humified organic carbon were greater than the initial ones. The values of available phosphorus (P) and potassium (K) determined at the end of experiment in Contr were almost the same as those recorded at the beginning of the research, confirming that the increases found in 80_OMWW and 120_OMWW plots were due to the OMWW applications. The findings suggest that repeated applications of OMWW could both sustain fodder crop performance and support soil fertility, with the possibility to recycle the organic amendment and reduce the risks of soil degradation.

ALTERNATIVE SUGAR BEET PRODUCTION USING SHALLOW TILLAGE AND MUNICIPAL SOLID WASTE FERTILISER

The application of conventional agricultural practices, e.g. deep soil tillage and repeated, plentiful mineral fertilisation, can lead to a progressive deterioration of soil fertility, especially in Mediterranean environments characterised by scanty rains and high summer temperatures. As a consequence, to maintain high levels of both crop productivity and soil organic matter and to improve some soil properties, a reduction of agricultural inputs and a greater supply of organic material are needed. In the light of these considerations, we carried out a two-year field experiment in Southern Italy to determine the effects of reduced soil tillage and municipal solid waste compost application on growth parameters, production and quality of sugar beet crops, and on both soil chemical characteristics and mineral nitrogen deficit. Two soil tillage depths were compared: conventional tillage, till 40–45 cm and shallow tillage, at 15–20 cm. Within each soil tillage, the following N-fertilising strategies were tested: (1) mineral fertilisation, with 100 kg N ha−1; (2) organic fertilisation with municipal solid waste compost at 100 kg N ha−1; (3) mixed fertilisation, with 50% of organic N as municipal solid waste compost, and 50% of mineral N; and (4) slow-release organic-mineral N fertiliser, at 100 kg N ha−1. All these treatments were compared with a lower level of mineral fertiliser at 50 kg N ha−1, and with an unfertilised control. Our findings show first the absence of a significant difference in root and sucrose yields between reduced tillage and deep tillage; as shown by roots (36.02 t ha−1) and sucrose (3.41 t ha−1) yields for reduced tillage and 35.76 and 3.51 t ha−1, respectively, for the deepest tillage. Secondly, among the N treatments, the mixed organic-mineral N fertilisation gave productions statistically not different from mineral N fertilisation; as shown by root yields (36.38 versus 36.40 t ha−1) and sucrose yields (3.56 versus 3.65 t ha−1). Third, the mixed organic-mineral N induced a reduction of 13.2% in α-amino N content by comparison with the mineral treatment of 100 kg N ha−1. Fourth, our results showed that the applications of the municipal solid waste compost increased the extracted and the humified organic carbon by +27.7 and +25.4%, compared with the mineral fertiliser, and did not raise the content of heavy metals. These findings highlighted that in Southern Italy it is sustainable to adopt alternative sugar beet production, safeguarding crops’ quantitative and qualitative performance, decreasing the production costs and using the natural resources better.

Bioassays and application of olive pomace compost on emmer: effects on yield and soil properties in organic farming

Abstract Composting olive oil pomace could solve the problem of disposal, by recycling this organic waste for agricultural purposes. Furthermore, application of composted organic waste could be a way to sustain both soil fertility and production, especially in organic farming. Therefore, the aim of this research was to evaluate the phytotoxicity and the effects of application of olive pomace composts on emmer performance and soil properties. Two types of olive pomace composts, with a different initial C/N ratio, were stopped at the active phase and processed until maturation. The obtained four olive pomace composts were compared with a commercial fertilizer in a two-year field experiment. Before the field trial, a bioassay was performed to assess phytotoxicity both for the raw pomace and the not-stabilized composts. Growing and yielding data for emmer were determined during the two-year period and soil characteristics were measured at the start and at the end of the experiment. The composts were not phytotoxic (germination index was higher than 90%) and their total organic carbon content was always higher than the minimum values established by the Italian fertilizers legislation. The emmer protein content was significantly higher in the matured compost treatment with low C/N, than in the other compost treatments. Its value was comparable with that of the commercial fertilizer, suggesting a good performance on crop yield quality. Although not significant, this compost showed an increase of 9.8% in grain yield compared with commercial fertilizer treatment. On the whole, it can be suggested that repeated compost application might preserve the soil organic carbon content and supply macronutrients to a crop.

Short-Term Agronomical Effects of Olive Oil Pomace Composts on Pisum arvense L. and Trifolium subterraneum L. and Impacts on Soil Properties

Olive oil pomace (OLP) contains organic matter and nutrients that could be recycled by composting and supplying it to crops, solving the problem of disposal. The effects of two OLP composts (C1 and C2) were assessed on two leguminous forage crops commonly cropped in the local livestock farms. In particular, C1 was applied on proteic pea and C2 on clover, compared with a mineral fertilizer (Min) and a commercial organic–mineral fertilizer (Org-min). The influence of composts on some soil chemical properties was also investigated. The application of C1 significantly increased proteic pea dry weight at the end of the cycle by 27.2% and 52.0% and grain yield by 23.2% and 43.6%, in comparison with Org-min and Min, respectively. The clover dry weight during the entire cycle was lower in C2, in comparison with the other treatments, while no significant difference was found between C2 and the Org-min treatment both in yield and plant height. Soil nitrate decreased from the beginning to the end of the trial in C1 and C2 plots by 22.8% and 50.9%, respectively. Soil phosphorous content significantly increased in Min by 32.4 and 41.7% compared to C1 and C2, respectively. These results showed that the substitution of commercial fertilizers with compost could be an environmentally sustainable solution. The high presence of heavy metals in compost should not affect soil application at least in this short-term trial.

Yield and Performance and Soil Properties of Organically Fertilized Fodder Crops

The aim of this study was to evaluate the effects of experimental amendments on yields of Trifolium subterraneum L., Pisum arvense L., and Lolium multiflorum Lam., and on soil characteristics. A two-year research was carried out comparing anaerobic digestate (AD) and olive-pomace compost (OPC) with mineral fertilizer (Min), commercial organic-mineral fertilizer (Org-min), and unfertilized control (Cont). Anaerobic digestate and OPC were firstly analyzed for their chemical characteristics. The most important parameters were recorded and soil properties were investigated. Anaerobic digestate showed the highest dry weight for ryegrass, the best yield in pea, and good level of dry matter in clover. Good responses were achieved by OPC. Anaerobic digestate increased total soil organic carbon by 14.4, 8.1 and 7.6% than Min, Org-min and Cont, respectively. Olive-pomace compost increased the same parameter by 16.3, 10.0, and 9.5%. The findings indicated the possibility to substitute mineral fertilizers with organic ones without decreasing yields and support soil fertility.

Suitability of Untreated and Composted Olive Mill By-Products as Amendments in Organic Olive Orchards

ABSTRACT. In the Mediterranean area, the proper soil application of olive pomace compost (OPC) and olive mill wastewater (OWW) could play a crucial role in replacing the annual losses of organic matter, thus sustaining agriculture. Therefore, the objectives of this five-year field trial were: (i) to investigate the effects of OWW and OPC, applied at different doses, on soil fertility in an organic Mediterranean olive grove; (ii) to assess the influence of treatments on production and quality responses of olive trees. In a randomized block experimental design, the following experimental treatments were compared: (i) OWW; (ii) OPC; (iii) the same olive pomace compost used in treatment (ii) distributed to supply a double rate of N per plant (OPCx2). These treatments were compared to: (a) commercial NPK organic-mineral fertilizer (Org-min); and (b) green manure of broad bean (GM). Soil parameters were analyzed to assess soil fertility at the beginning of the field trial and in the medium and longer term. At harvest, agronomical performance of treatments was also evaluated. At the end of the field trial, olive pomace compost (mean of OPC and OPCx2) significantly increased total organic carbon by 47.5% compared to Org-min, and the humified organic carbon values were significantly higher for OWW, OPC, and OPCx2, as compared to GM. The values for olive yield components in GM were lower than in OPC and OWW. Therefore, results showed that OWW and OPC application could be a suitable substitute of traditional methods (GM) to improve overall soil fertility and sustain yield in organic olive grove.