Thesis (Msc. (Agriculture)) --University of Limpopo, 2011 / The impact of agricultural chemicals on the environment has come under close scrutiny in the country of South Africa, for that reason, we are investigating alternative and appropriate methods for nutrients management. The objective of the study was to assess infield spatial variability of soil nutrients in a uniformly managed corn field, and (ii) to recommend method that can potentially help corn (Zea mays L.) producers in Limpopo Province to enhance grain yield with optimal utilization of resources. The study was conducted at Syferkuil agricultural experimental farm (23o50’ S; 29 o40’ E) of the University of Limpopo, in the northern semi-arid region of South Africa. Prior to planting of corn on this uniformly managed 7 ha portion of a 1 705 ha farm, the field was mapped with Ag132 Trimble differentially corrected global positioning system (DGPS) equipped with Field Rover II® GIS mapping software. Land suitability assessment for corn was conducted before planting and the field was classified for suitability as S1 based on FAO guidelines for irrigated agriculture and South African Binomial System of Soil classification. Soils and corn leaf sample parameters, including N were collected and measured from geo-referenced locations on a 40 x 40 m grid. Nutrient distribution spatial maps were produced with Surfer software 8.0. There was a significant variability (P≤0.05) of soil nutrients and pH across the corn field. Corn grain yield ranged from 2.7 to 6.3 Mg ha-1. For a land suitability class of S1 under linear irrigation in a semi-arid environment, these grain yields were considered lower. This lower grain yields can be linked to variability of soil nutrients, and pH because the field was classified suitable according to FAO guidelines. This field, with its significant variability of nutrients and pH that resulted in lower grain yields, is potentially a good field for precision agriculture IX methods of nutrient management such site-specific management zones for environmental quality and economic efficiency. Keywords: Maize, Small-scale farming, Soil nutrient management, and Spatial variability

Submitted by Carlos Henrique Augusto null (caheaug@gmail.com) on 2018-03-23T19:43:51Z No. of bitstreams: 1 ZONAS HOMOGÊNEAS DE MANEJO POR MEIO DE VARIÁVEIS EDAFOCLIMÁTICAS E DE PRODUTIVIDADE.pdf: 4887969 bytes, checksum: f9f7dded5e127da5325c1b1fbf7b57dd (MD5) / Approved for entry into archive by Maria Lucia Martins Frederico null (mlucia@fca.unesp.br) on 2018-03-23T19:59:20Z (GMT) No. of bitstreams: 1 augusto_ch_me_botfca.pdf: 4887928 bytes, checksum: 78e2387068a46ce3ac48c992ecb5c599 (MD5) / Made available in DSpace on 2018-03-23T19:59:20Z (GMT). No. of bitstreams: 1 augusto_ch_me_botfca.pdf: 4887928 bytes, checksum: 78e2387068a46ce3ac48c992ecb5c599 (MD5) Previous issue date: 2018-02-01 / O aumento da população mundial e a limitada área disponível para a produção de alimentos, exige que busquemos cada vez mais técnicas e tecnologias que aumentem a produtividade das áreas agrícolas. A produtividade de uma determinada cultura depende de diversos fatores, e conhecer os fatores que mais influenciam a determinação do seu potencial produtivo pode contribuir para a tomada de decisão em relação à utilização e gestão de recursos. Utilizando dados de monitores de colheita da cultura da soja nas safras de 08/09, 10/11, 11/12, 12/13, 14/15 e 15/16, dados de precipitação destes anos, mapa de Condutividade Elétrica (CE) e das características químicas do solo para as safras de 09/10, 13/14, 14/15 e 15/16, este trabalho teve o objetivo de identificar os fatores mais relevantes para a determinação da produtividade da soja para auxiliar na determinação de Zonas Homogêneas de Manejo (ZHM) baseadas nestas características críticas. Comprovou-se que a disponibilidade de água é a principal determinante da produtividade da soja nas condições estudadas, sendo que a precipitação no mês de setembro, mês de implantação da cultura, apresentou-se como o fator mais crítico. Utilizando o mapa de produtividade média da cultura durante os anos estudados e o mapa de CE, foi possível identificar as áreas de potencial produtivo, mas a definição de ZHM mostrou-se desafiadora pois as características químicas do solo apresentaram alta variabilidade temporal, dificultando a determinação do manejo que poderia melhor explorar as áreas de maior ou menor potencial produtivo. / The growing world population and the limited area available for food production requires us to progressively seek techniques and technologies that increase the yield of agricultural crops. The yield of a crop depends on several factors and knowing the factors that most influences its yield potential can contribute to the decision making process regarding the use and management of resources. Using data from soybean yield monitors of 08/09, 10/11, 11/12, 12/13, 14/15 and 15/16 season, precipitation data from these years, Electric Conductivity (EC) map and the chemical characteristics of the soil for the 9/10, 13/14, 14/15 and 15/16 crops, this work had the objective of identifying the most relevant factors that determine soybean yield to assist in the determination of Homogeneous Management Zones (HMZ) based on these critical characteristics. The availability of water was the main factor of soybean yield under the conditions the study was carried out, and the precipitation in September was the most critical factor, being the month in which the crop was seeded. Using the average productivity map and the EC map, it was possible to identify areas of yield potential, but the definition of HMZ was challenging because the chemical characteristics of the soil had high temporal variability, making it difficult to determine the best management to explore the areas of greater or lesser yield potential.