In Lombok (Indonesia), annual cropping patterns in irrigated areas are divided into three cropping cycles of four months each. In better irrigation schemes, there are normally two irrigated flooded-rice crops, i.e. wet season and dry season lowland rice crops in sequence, followed by one non-rice crop cycle during the driest months (this is referred to as the twice-rice system). In less developed irrigation schemes, one lowland rice crop is normally grown during the rainy season, followed during the driest months by two cycles of non-rice crops, or a non-rice crop and a fallow (this is referred to as the once-rice system). In rainfed areas, especially in the vertisol soil areas, there are upland rice systems in the highland or hillsides, and “Gora” (dry seeded-flooded) rice systems in the lowland. In this area, rice is grown only once a year during the rainy season of the monsoon. Farmers in Lombok do not normally fertilise the non-rice crops such as soybean and mungbean grown following rice, and application rates of fertiliser to rice have fallen since the economic crisis in 1998. Therefore phosphorus (P) deficiency may be expected, which may explain the very low yields of soybean and mungbean achieved by farmers in Lombok. With low P, arbuscular mycorrhizas (AM) might be expected to play an important role in plant nutrition, but inoculation with arbuscular mycorrhizal fungi (AMF) increased root colonisation and yield of these crops in a recent field experiment in Lombok. There had been no survey of AMF populations in rice-based systems in Lombok prior to the work reported here, and little such work anywhere internationally. Therefore, an extensive survey was conducted in Lombok on the two main soil types with rice-based systems. Another field survey was conducted in the Riverina rice-growing area (Australia), as a comparative study to the Lombok survey. In Lombok, rice systems with longer total annual flooding duration had lower populations compared with upland or Gora rice systems. It was therefore suggested that the lower colonisation level in flooded rice was due to the flooded conditions, as well as soil chemical properties associated with flooded conditions, rather than the rice plant itself. There are options for improving AMF population for better growth of non-rice rotation crops, or even for rice crop in Lombok as fertilisers become less affordable and their use on flooded rice is declining. The easiest option is to inoculate AM fungi in the nursery or to make nursery beds in a paddock previously cropped with AMF-stimulating species, such as soybean, to start infection on rice seedlings, which should be better with a dry nursery. The second option is to modify the technique of growing rice, such as applying the SRI (System of Rice Intensification) principles, in which rice is grown without flooded conditions but intermittent short flooded and upland conditions. This will keep the soil in an aerobic condition much of the time and should facilitate the development of beneficial microbial populations and activities in the soil, such as AMF and nitrogen fixers. The SRI method has been reported to increase rice yield dramatically, even in soil with low fertility levels. / Doctor of Philosophy (PhD)

L’intensificazione sostenibile delle pratiche agricole rappresenta un paradigma per il passaggio da sistemi agricoli tradizionali all’applicazione di tecnologie e tecniche moderne per la produzione agricola. A livello globale si è diffuso l’interesse verso il modello di Agricoltura Sostenibile (AS), in vista di alcuni problemi che possono minacciare la sicurezza alimentare mondiale: crescita della popolazione mondiale, cambiamenti nella domanda delle produzioni agricole, percentuale elevata di persone sottonutrite, cambiamenti climatici, diminuzione delle risorse naturali. Il progetto “Produzione di cibo appropriato: sufficiente, sicuro, sostenibile”, ancora in corso, lavora per raggiungere alcuni scopi: (1) rilevare e valutare la disponibilità quantitativa e qualitativa degli alimenti destinati al consumo umano, (2) proporre nuovi sistemi di produzione agro-zootecnica, (3) sviluppare tecniche appropriate per processare e conservare gli alimenti, al fine di ottenere uno stato di sicurezza alimentare e sostenibilità ambientale ed economica. L’obiettivo generale di questo lavoro è quello di mostrare quali sono le possibili alternative ai sistemi agricoli tradizionali, sia nei Paesi Sviluppati sia in quelli in Via di Sviluppo, al fine di aumentarne l’efficienza e diminuirne gli impatti sull’ambiente, aumentando lo stato globale di sicurezza alimentare. Per i Paesi in Via di Sviluppo l’attenzione si concentra sulle pratiche di sviluppo rurale integrato, al fine di implementare quantitativamente la produzione alimentare e, conseguentemente, la sicurezza alimentare, preservando nel contempo l'ambiente. Per i Paesi Sviluppati, in cui i rendimenti agricoli sono già potenzialmente molto elevati, l’attenzione viene focalizzata sul migliorare la produttività del suolo, riducendo gli input esterni e le emissioni di gas ad effetto serra, attraverso l’adozione di sistemi agricoli conservativi. / Sustainable intensification of agricultural practices represents a paradigm shift from traditional farming systems to the application of modern technologies and techniques to crop production. At global level it has been widespread interest towards Sustainable Agriculture (SA) model, in view of some issues that will may threaten the world food security: growing world population, changes in agricultural product’s demand, high prevalence of undernourishment, climate changes, decreasing of natural resources. The project “Production of proper food: sufficient, safe, sustainable" is still working to achieve some purposes: (1) to detect the availability quantity and quality of food for human consumption, (2) to propose new agro-livestock production systems, (3) to develop appropriate techniques for processing and storage of foodstuffs, in order to achieve food security, environmental and economic sustainability. The objective of this work is to show what are the possible alternatives ways at traditional agricultural systems, both in Developed and Developing Countries, in order to increase the efficiency and to decrease the impacts on the environment, raising a global condition of food security. For Developing Countries the attention is focused on integrated rural development practices in order to implement food production and the state of food security, while preserving the environment. For Developed Countries, in which yields are already potentially higher, the attention is focused on enhance soil productivity while reducing external farming input and greenhouse gases emission by the adoption of conservation agricultural systems.

<div>The goal of this research was to improve crop yield and quality and enhance nutrient use efficiency of aquaponics for the development of sustainable aquaponic production system. Aquaponics is the integration of aquaculture and hydroponics by recirculating water and residual nutrients resulting from aquaculture wastewater into hydroponic crop production. The project had four objectives. The first objective was to characterize nutrient composition and accumulation in recirculating water and plant parts of tomato, basil, and lettuce grown in aquaponic systems, and to compare their growth and yield with those grown in hydroponic systems. The second objective was to determine the effects of feeding management regime on water quality, crop yield and quality, and N use efficiency for vegetable and herb production in recirculating aquaponics in comparison to hydroponics. The third objective was to optimize water-flow rate for efficient aquaponic system for maximum crop yield. The fourth objective was to investigate and compare the N and P mass balance between aquaponics and hydroponics. Four conclusions were determined that 1) Aquaponic solution was deficient in Ca and/or Mg leading to plant nutrient deficiency but sufficient or high in P; And luxuriant nutrient profiles in hydroponics are not necessary to enhance crop yield in aquaponics as long as key factors affecting crop yield are identified and properly addressed. 2) Uniform feeding regime improved water quality by reducing toxic ions and enhancing initial nutrient availability and considerably increased the yield, quality and nitrogen use efficiency (NUE) of crops in aquaponics as close or similar to those in hydroponics. 3) Flow rate is an important factor affecting water quality parameters and optimizing flow rate is essential to maximize aquaponic crop production and improve energy efficiency; High hydraulic loading rate at 3.3 m3/m2-day improved performance and yield of all crops in an aquaponics system regardless of their growth rate, but the water hydraulic loading rate for fast-growing and medium-growing crops can be reduced to 2.2 m3/m2-day without production reduction. 4) Plant species had significant influence on N and P removal and mass balance in aquaponics and hydroponics; Fruity vegetables showed better growth adaption in aquaponic system, while yields of leafy vegetables may be reduced when grown in aquaponics than hydroponics; Aquaponics is more efficient than hydroponics releasing less environmental wastes, however, N and P use efficiency in aquaponics and hydroponics can be further improved via proper management.</div><div>The important findings obtained from this research will fill the knowledge gap in aquaponic research and provide new management strategies to improve quantitative study of aquaponic crop production and new management strategies for cultivating crops in aquaponics. The findings will also greatly contribute to the commercial aquaponic development, and ultimately improve food security and resource use efficiency in the US and global agricultural production.</div>