Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2017-10-13T12:25:06Z No. of bitstreams: 1 2016 - Pedro Antonio Pa??.pdf: 2520523 bytes, checksum: dbda485ebbcb8e6720ce729890cb05ad (MD5) / Made available in DSpace on 2017-10-13T12:25:06Z (GMT). No. of bitstreams: 1 2016 - Pedro Antonio Pa??.pdf: 2520523 bytes, checksum: dbda485ebbcb8e6720ce729890cb05ad (MD5) Previous issue date: 2016-03-04 / This study aimed to evaluate the performance of a succession of corn and bean, submitted to organic management associated with green manure from a mixture of species with different spatial arrangements. The experiment was conducted in the Sistema Integrado de Produ??o Agroecol?gica - SIPA, located in Serop?dica - RJ, Brazil. The statistical design was a completely randomized blocks with six treatments and four replicates, totaling twenty four plots. In this sense, the experiment was planned in two parts, the first part was the study of spatial arrangements of planting, consisting in a mixture (Canavalia ensiformis, Crotalaria juncea and Helianthus annuus) of cover crops species (ECS) for green manure contemplating: intercropping with corn (cv. Caatingueiro) in double rows. The treatments consisted : ECS haul sowing; ECS furrow sowing; ECS haul sowing in a intercropping with corn; ECS furrow sowing in a intercropping with corn; corn monoculture; fallow (control). The evaluated parameters were: cover soil provided by ECS; fresh and dry biomass productivity; chemical composition of ECS aerial part; and corn grains productivity. The second part of the experiment took place in the same area, and bean (cv. Constanza) was planted in the same plots of the first part of the experiment. It was evaluated the influence of cover crops species on weed reinfestation and on the productivity of beans. As a general conclusion it was observed that the ECS covered the soil faster than the current spontaneous vegetation on fallow did. The fresh and dry biomass productivity and the cumulative quantity of nutrients in the biomass of the treatments that took in the ECS were higher than in corn monoculture. It was noted that the presence of the ECS influenced positively on weed reinfestation control. The corn grains productivity was lower when intercropping with ECS, however, the yield of beans was not influenced. The sowing way, haul or furrow, showed no differences, one interesting finding because the smallholder have freedom to choice the sowing way, without concern with related losses. / O presente estudo teve como objetivo avaliar o desempenho produtivo de uma sucess?o envolvendo milho e feijoeiro, submetidos ao manejo org?nico, associada ? aduba??o verde formada de uma mistura de esp?cies com diferentes arranjos espaciais. O experimento foi conduzido no Sistema Integrado de Produ??o Agroecol?gica ? SIPA (UFRRJ/Embrapa Agrobiologia/PESAGRO-RIO), localizado no munic?pio de Serop?dica, regi?o da Baixada Fluminense, RJ. O delineamento estat?stico adotado foi o de blocos casualizados, com seis tratamentos e quatro repeti??es, totalizando vinte e quatro parcelas. Neste sentido, o experimento foi planejado em duas partes, onde a primeira foi o estudo de arranjos espaciais de plantio composta por uma mistura de esp?cies (Canavalia ensiformis, Crotalaria juncea e Helianthus annuus) de plantas de cobertura do solo (ECS) para aduba??o verde, contemplando cultivos consorciados com o milho (variedade Caatingueiro) em fileiras duplas. Os tratamentos constaram de: ECS semeadas a lan?o; ECS semeadas em sulcos; ECS semeadas a lan?o em cons?rcio com o milho; ECS semeadas em sulcos em cons?rcio com o milho; monocultivo de milho; pousio (controle). Avaliou-se a cobertura do solo proporcionada pelas ECS; produtividade de biomassa fresca e seca; composi??o qu?mica da parte a?rea das esp?cies de cobertura do solo; e a produtividade de gr?os de milho. Na segunda parte do trabalho, na mesma ?rea em sucess?o, cultivou-se o feijoeiro (cv. Constanza) nas parcelas empregadas na primeira parte. Avaliou-se a influ?ncia das esp?cies de cobertura do solo na reinfesta??o de esp?cies espont?neas e a produtividade de gr?os de feij?o. Como conclus?o geral, observou-se que as ECS cobriram com maior velocidade o terreno do que a vegeta??o espont?nea presente no sistema em pousio. As produtividades de biomassa fresca e seca da parte a?rea e a quantidade acumulada de nutrientes na biomassa a?rea dos tratamentos que continham as ECS foram maiores do que no monocultivo do milho. Notou-se que a presen?a das ECS influenciou positivamente no controle da reinfesta??o das esp?cies espont?neas. A produtividade de gr?os de milho foi menor quando consorciado com as ECS, no entanto, a produtividade de gr?os de feij?o n?o foi influenciada. O modo de semeadura, a lan?o ou em sulcos, n?o demonstrou diferen?as nas avalia??es realizadas, sendo um dado interessante pelo fato do agricultor, dessa maneira, ter livre escolha quanto ao modo de semeadura, sem ter a preocupa??o de preju?zos correlacionados

The potential for relay intercropping and double cropping was assessed in field trials over three consecutive years at Gatton, Queensland. The rationale was to use controlled traffic technology to facilitate relay and double cropping and thus research a cropping system that could exploit late winter crop rainfall. In Field Trial I, grain sorghum and sunflower, broadacre crops already grown within the Southern and Darling Downs regions of Queensland and New South Wales were intercropped into wheat; sunflower was intercropped with wheat in Field Trial II. Sole summer plantings were made at the same time as intercrops were planted. The wheat crop was cut and stubble removed to facilitate this. Various planting dates (three for Field Trial I; four for Field Trial II) for the relayed summer crops were used to determine if an optimum planting time existed. Plant height, tiller number, light interception, grain yield, soil moisture and economic return were used as parameters to compare the intercrop with sole plantings in Field Trial I. Grain yield, soil moisture, rainfall infiltration and economic return were measured in Field Trial II. Research also involved the modification and testing of a tractor to carry out the sowing of the intercrop. In Field Trial I, light interception was shown to vary at different stages of the wheat crop and the use of these stages to determine optimum planting dates of the relay crop is suggested. In both trials, no differences were recorded in the grain yield between intercropped and sole cropped wheat treatments suggesting the trafficking of the plot did not affect the wheat. As neither sorghum or sunflower established as intercrops, competition was not a factor in affecting wheat yields. Moisture readings in both trials showed little change below a depth of 100 cm; however some treatment differences were present at shallower depths. In Field ii Trial I, sole summer sorghum, especially the first planting date, showed reduced water capture/ higher soil evaporation due to wheat removal initially and later transpiration loss due to crop growth and increased weed pressure. Sole wheat treatments showed increased moisture storage after harvest due to lack of water use by the crop and increased infiltration/reduced runoff due to stubble retention. Improved soil moisture recharge after rainfall events was apparent in double cropped treatments suggesting not only improved water utilisation but also improved capture and storage is possible within this system. Sorghum, commonly used throughout south eastern Queensland as a summer crop option, proved unsuitable for relay intercropping in Field Trial I for Planting Dates 1 and 2. Minimum soil temperatures for these plantings were marginal as they were close to the 15o Celsius level recommended for sorghum. However, even though establishment was poor for the intercropped plantings, it was higher for sole sorghum plantings. Wheat allelopathic effects may be involved. To avoid the temperature limitations of sorghum, sunflower was selected as an alternative intercrop in the later planting dates of Field Trial I and all dates for Field Trial II. Reasons for the poor establishment and yield of sunflowers in the earlier intercrop planting dates compared to sole plantings remain unknown but also may be related to allelopathic effects from intercropped wheat. Low soil temperature was not a factor affecting establishment Yields for planting dates were recorded in the intercropped sunflower treatments for Field Trial II and the optimal planting time for sunflowers in a wheat/sunflower relay intercrop was identified as when physiological maturity of the wheat had occurred. This may relate to the wheat crop stage. In Field Trial II, no significant differences in soil moisture were recorded between treatments from overall water use for the trial period. There were differences in water use between intercropped and sole cropped treatments for iii some rainfall events. Three rainfall events were chosen for closer study in each of the field trials conducted. Each event varied in the length and time as well as the duration and intensity of the rain that fell for the period. For the first rainfall period the moisture content of the first planting date of the sole summer treatment and to a lesser extent the second planting date of the same treatment increased, most likely due to wheat removal. In the third rainfall period the double cropped sunflower treatment with stubble tended to store less moisture and this may be due to the active crop growth at this time. It was evident in both field trials of the need for an effective weed control program in the intercrop plots. Weeds were controlled in wheel tracks by glyphosate sprays. Cultural methods may help but a herbicide suitable for both components of the intercrop would be very useful. A tractor was successfully modified to a 3 metre wheelspace and a clearance of 70 cm. This proved sufficient for planting the relay intercrop in Field Trial II without negatively affecting the yield of the standing crop. The row spacing of 18 cm for wheat in a 3 metre fixed bed and wheeltrack configuration assisted with guidance and interplanting of the relay crop. The relay crop was sown as single alternating rows.

Intercropping, defined as two or more crops grown on the same land area at the same time, is a sustainable alternative to sole crops. Intercropping has been associated with multiple benefits, such as increased nutrient and soil organic carbon (SOC) cycling, decreased soil erosion and increased carbon (C) sequestration. A common intercropping practice is to integrate cereal and legume crops such as maize (Zea mays L.), and soybean (Glycine max (L.) Merr.). Most studies on intercropping have focused on yield, weed control, and land use efficiency in the tropics. Few studies have researched C and nitrogen (N) dynamics in temperate intercrops, with respect to soybean and maize residue stabilization. Soil from Balcarce, Argentina, was incubated for 140 days with soybean, maize, or no residue. Throughout the incubation, results illustrated the effect of residue application upon the soil, specifically through significantly higher amounts of light fraction (LF) C and LFN concentrations, soil microbial biomass (SMB) C and SMBN concentrations, higher microbial diversity, lower N2O production rates, in addition to distinct isotopic values in soil fractions and CO2 (p<0.05). Furthermore, it was observed from δ15N-TN and δ15N-LF that treatments with soybean residues included had higher N cycling (p<0.05), emphasizing the importance of including N-fixing legumes in complex agroecosystems. Significant changes over time in SMB and SMCS characteristics, and isotope values (p<0.05) indicated the preferential utilization of relatively young and easily accessible litter. Furthermore, the loss of labile material over the incubation resulted in more recalcitrant forms (such as older C and lignin) to be utilized. Slightly higher SOC, TN, LFC and LFN concentrations, as well as lower CO2 production rates suggested 2:3 (rows of maize:rows of soybean) as a more desirable intercrop design for C sequestration. The 1:2 intercrop design was observed to be more beneficial for microbial community structure, furthering the idea that intercropping is a beneficial alternative to sole cropping. This study improves knowledge in residue stabilization and C sequestration in complex agroecosystems, providing encouragement for the implementation of more sustainable management practices.

Two studies were carried out in the Morgan Arboretum of McGill University to explore the agroforestry potential of some native tree species of Southern Quebec. In the first study, soil chemical characteristics under basswood (Tilia americana L.), white ash (Fraxinus americana L.) and bitternut hickory (Carya cordiformis Wang. K. Koch) in relation to sugar maple (Acer saccharum Marsh.) were assessed in natural stands. Soil pH was highest under white ash and was lowest under bitternut hickory. Soil NO$ sb3 sp-$ was low under basswood compared to white ash. Soil pH and exchangeable soil Ca$ sp{2+}$ and Mn$ sp{2+}$ decreased with an increase in basal area and exchangeable soil K$ sp+$ decreased (p = 0.07) with an increase in the proportion of sugar maple relative to total basal area. / In the second study, the effects of black walnut (Juglans nigra L.) on growth and nutrient content of lettuce (Lactuca sativa L.), kale (Brussica oleracea L.), parsley (Petroselinum crispum) and Swiss chard (Beta vulgaris L.) in an alley cropping system were determined. The experiment was carried out in a randomized complete block design with repeated measures. All vegetables survived in the black walnut plantation and in the open field. The order of sensitivity to growth under black walnut was Swiss chard $>$ kale $>$ lettuce $>$ parsley. Low light intensity in the plantation likely decreased plant dry weights and nutrient content. Generally plant N, P and K concentrations were higher in the plantation while Ca, Mg and Mn concentrations were higher in the open field, possibly due to an antagonistic effect of high soil K$ sp+$ content in the plantation and to inhibitory effects of black walnut.

Intercropping, defined as two or more crops grown on the same land area at the same time, is a sustainable alternative to sole crops. Intercropping has been associated with multiple benefits, such as increased nutrient and soil organic carbon (SOC) cycling, decreased soil erosion and increased carbon (C) sequestration. A common intercropping practice is to integrate cereal and legume crops such as maize (Zea mays L.), and soybean (Glycine max (L.) Merr.). Most studies on intercropping have focused on yield, weed control, and land use efficiency in the tropics. Few studies have researched C and nitrogen (N) dynamics in temperate intercrops, with respect to soybean and maize residue stabilization. Soil from Balcarce, Argentina, was incubated for 140 days with soybean, maize, or no residue. Throughout the incubation, results illustrated the effect of residue application upon the soil, specifically through significantly higher amounts of light fraction (LF) C and LFN concentrations, soil microbial biomass (SMB) C and SMBN concentrations, higher microbial diversity, lower N2O production rates, in addition to distinct isotopic values in soil fractions and CO2 (p<0.05). Furthermore, it was observed from δ15N-TN and δ15N-LF that treatments with soybean residues included had higher N cycling (p<0.05), emphasizing the importance of including N-fixing legumes in complex agroecosystems. Significant changes over time in SMB and SMCS characteristics, and isotope values (p<0.05) indicated the preferential utilization of relatively young and easily accessible litter. Furthermore, the loss of labile material over the incubation resulted in more recalcitrant forms (such as older C and lignin) to be utilized. Slightly higher SOC, TN, LFC and LFN concentrations, as well as lower CO2 production rates suggested 2:3 (rows of maize:rows of soybean) as a more desirable intercrop design for C sequestration. The 1:2 intercrop design was observed to be more beneficial for microbial community structure, furthering the idea that intercropping is a beneficial alternative to sole cropping. This study improves knowledge in residue stabilization and C sequestration in complex agroecosystems, providing encouragement for the implementation of more sustainable management practices.

The potential for relay intercropping and double cropping was assessed in field trials over three consecutive years at Gatton, Queensland. The rationale was to use controlled traffic technology to facilitate relay and double cropping and thus research a cropping system that could exploit late winter crop rainfall. In Field Trial I, grain sorghum and sunflower, broadacre crops already grown within the Southern and Darling Downs regions of Queensland and New South Wales were intercropped into wheat; sunflower was intercropped with wheat in Field Trial II. Sole summer plantings were made at the same time as intercrops were planted. The wheat crop was cut and stubble removed to facilitate this. Various planting dates (three for Field Trial I; four for Field Trial II) for the relayed summer crops were used to determine if an optimum planting time existed. Plant height, tiller number, light interception, grain yield, soil moisture and economic return were used as parameters to compare the intercrop with sole plantings in Field Trial I. Grain yield, soil moisture, rainfall infiltration and economic return were measured in Field Trial II. Research also involved the modification and testing of a tractor to carry out the sowing of the intercrop. In Field Trial I, light interception was shown to vary at different stages of the wheat crop and the use of these stages to determine optimum planting dates of the relay crop is suggested. In both trials, no differences were recorded in the grain yield between intercropped and sole cropped wheat treatments suggesting the trafficking of the plot did not affect the wheat. As neither sorghum or sunflower established as intercrops, competition was not a factor in affecting wheat yields. Moisture readings in both trials showed little change below a depth of 100 cm; however some treatment differences were present at shallower depths. In Field ii Trial I, sole summer sorghum, especially the first planting date, showed reduced water capture/ higher soil evaporation due to wheat removal initially and later transpiration loss due to crop growth and increased weed pressure. Sole wheat treatments showed increased moisture storage after harvest due to lack of water use by the crop and increased infiltration/reduced runoff due to stubble retention. Improved soil moisture recharge after rainfall events was apparent in double cropped treatments suggesting not only improved water utilisation but also improved capture and storage is possible within this system. Sorghum, commonly used throughout south eastern Queensland as a summer crop option, proved unsuitable for relay intercropping in Field Trial I for Planting Dates 1 and 2. Minimum soil temperatures for these plantings were marginal as they were close to the 15o Celsius level recommended for sorghum. However, even though establishment was poor for the intercropped plantings, it was higher for sole sorghum plantings. Wheat allelopathic effects may be involved. To avoid the temperature limitations of sorghum, sunflower was selected as an alternative intercrop in the later planting dates of Field Trial I and all dates for Field Trial II. Reasons for the poor establishment and yield of sunflowers in the earlier intercrop planting dates compared to sole plantings remain unknown but also may be related to allelopathic effects from intercropped wheat. Low soil temperature was not a factor affecting establishment Yields for planting dates were recorded in the intercropped sunflower treatments for Field Trial II and the optimal planting time for sunflowers in a wheat/sunflower relay intercrop was identified as when physiological maturity of the wheat had occurred. This may relate to the wheat crop stage. In Field Trial II, no significant differences in soil moisture were recorded between treatments from overall water use for the trial period. There were differences in water use between intercropped and sole cropped treatments for iii some rainfall events. Three rainfall events were chosen for closer study in each of the field trials conducted. Each event varied in the length and time as well as the duration and intensity of the rain that fell for the period. For the first rainfall period the moisture content of the first planting date of the sole summer treatment and to a lesser extent the second planting date of the same treatment increased, most likely due to wheat removal. In the third rainfall period the double cropped sunflower treatment with stubble tended to store less moisture and this may be due to the active crop growth at this time. It was evident in both field trials of the need for an effective weed control program in the intercrop plots. Weeds were controlled in wheel tracks by glyphosate sprays. Cultural methods may help but a herbicide suitable for both components of the intercrop would be very useful. A tractor was successfully modified to a 3 metre wheelspace and a clearance of 70 cm. This proved sufficient for planting the relay intercrop in Field Trial II without negatively affecting the yield of the standing crop. The row spacing of 18 cm for wheat in a 3 metre fixed bed and wheeltrack configuration assisted with guidance and interplanting of the relay crop. The relay crop was sown as single alternating rows.

The potential for relay intercropping and double cropping was assessed in field trials over three consecutive years at Gatton, Queensland. The rationale was to use controlled traffic technology to facilitate relay and double cropping and thus research a cropping system that could exploit late winter crop rainfall. In Field Trial I, grain sorghum and sunflower, broadacre crops already grown within the Southern and Darling Downs regions of Queensland and New South Wales were intercropped into wheat; sunflower was intercropped with wheat in Field Trial II. Sole summer plantings were made at the same time as intercrops were planted. The wheat crop was cut and stubble removed to facilitate this. Various planting dates (three for Field Trial I; four for Field Trial II) for the relayed summer crops were used to determine if an optimum planting time existed. Plant height, tiller number, light interception, grain yield, soil moisture and economic return were used as parameters to compare the intercrop with sole plantings in Field Trial I. Grain yield, soil moisture, rainfall infiltration and economic return were measured in Field Trial II. Research also involved the modification and testing of a tractor to carry out the sowing of the intercrop. In Field Trial I, light interception was shown to vary at different stages of the wheat crop and the use of these stages to determine optimum planting dates of the relay crop is suggested. In both trials, no differences were recorded in the grain yield between intercropped and sole cropped wheat treatments suggesting the trafficking of the plot did not affect the wheat. As neither sorghum or sunflower established as intercrops, competition was not a factor in affecting wheat yields. Moisture readings in both trials showed little change below a depth of 100 cm; however some treatment differences were present at shallower depths. In Field ii Trial I, sole summer sorghum, especially the first planting date, showed reduced water capture/ higher soil evaporation due to wheat removal initially and later transpiration loss due to crop growth and increased weed pressure. Sole wheat treatments showed increased moisture storage after harvest due to lack of water use by the crop and increased infiltration/reduced runoff due to stubble retention. Improved soil moisture recharge after rainfall events was apparent in double cropped treatments suggesting not only improved water utilisation but also improved capture and storage is possible within this system. Sorghum, commonly used throughout south eastern Queensland as a summer crop option, proved unsuitable for relay intercropping in Field Trial I for Planting Dates 1 and 2. Minimum soil temperatures for these plantings were marginal as they were close to the 15o Celsius level recommended for sorghum. However, even though establishment was poor for the intercropped plantings, it was higher for sole sorghum plantings. Wheat allelopathic effects may be involved. To avoid the temperature limitations of sorghum, sunflower was selected as an alternative intercrop in the later planting dates of Field Trial I and all dates for Field Trial II. Reasons for the poor establishment and yield of sunflowers in the earlier intercrop planting dates compared to sole plantings remain unknown but also may be related to allelopathic effects from intercropped wheat. Low soil temperature was not a factor affecting establishment Yields for planting dates were recorded in the intercropped sunflower treatments for Field Trial II and the optimal planting time for sunflowers in a wheat/sunflower relay intercrop was identified as when physiological maturity of the wheat had occurred. This may relate to the wheat crop stage. In Field Trial II, no significant differences in soil moisture were recorded between treatments from overall water use for the trial period. There were differences in water use between intercropped and sole cropped treatments for iii some rainfall events. Three rainfall events were chosen for closer study in each of the field trials conducted. Each event varied in the length and time as well as the duration and intensity of the rain that fell for the period. For the first rainfall period the moisture content of the first planting date of the sole summer treatment and to a lesser extent the second planting date of the same treatment increased, most likely due to wheat removal. In the third rainfall period the double cropped sunflower treatment with stubble tended to store less moisture and this may be due to the active crop growth at this time. It was evident in both field trials of the need for an effective weed control program in the intercrop plots. Weeds were controlled in wheel tracks by glyphosate sprays. Cultural methods may help but a herbicide suitable for both components of the intercrop would be very useful. A tractor was successfully modified to a 3 metre wheelspace and a clearance of 70 cm. This proved sufficient for planting the relay intercrop in Field Trial II without negatively affecting the yield of the standing crop. The row spacing of 18 cm for wheat in a 3 metre fixed bed and wheeltrack configuration assisted with guidance and interplanting of the relay crop. The relay crop was sown as single alternating rows.

The potential for relay intercropping and double cropping was assessed in field trials over three consecutive years at Gatton, Queensland. The rationale was to use controlled traffic technology to facilitate relay and double cropping and thus research a cropping system that could exploit late winter crop rainfall. In Field Trial I, grain sorghum and sunflower, broadacre crops already grown within the Southern and Darling Downs regions of Queensland and New South Wales were intercropped into wheat; sunflower was intercropped with wheat in Field Trial II. Sole summer plantings were made at the same time as intercrops were planted. The wheat crop was cut and stubble removed to facilitate this. Various planting dates (three for Field Trial I; four for Field Trial II) for the relayed summer crops were used to determine if an optimum planting time existed. Plant height, tiller number, light interception, grain yield, soil moisture and economic return were used as parameters to compare the intercrop with sole plantings in Field Trial I. Grain yield, soil moisture, rainfall infiltration and economic return were measured in Field Trial II. Research also involved the modification and testing of a tractor to carry out the sowing of the intercrop. In Field Trial I, light interception was shown to vary at different stages of the wheat crop and the use of these stages to determine optimum planting dates of the relay crop is suggested. In both trials, no differences were recorded in the grain yield between intercropped and sole cropped wheat treatments suggesting the trafficking of the plot did not affect the wheat. As neither sorghum or sunflower established as intercrops, competition was not a factor in affecting wheat yields. Moisture readings in both trials showed little change below a depth of 100 cm; however some treatment differences were present at shallower depths. In Field ii Trial I, sole summer sorghum, especially the first planting date, showed reduced water capture/ higher soil evaporation due to wheat removal initially and later transpiration loss due to crop growth and increased weed pressure. Sole wheat treatments showed increased moisture storage after harvest due to lack of water use by the crop and increased infiltration/reduced runoff due to stubble retention. Improved soil moisture recharge after rainfall events was apparent in double cropped treatments suggesting not only improved water utilisation but also improved capture and storage is possible within this system. Sorghum, commonly used throughout south eastern Queensland as a summer crop option, proved unsuitable for relay intercropping in Field Trial I for Planting Dates 1 and 2. Minimum soil temperatures for these plantings were marginal as they were close to the 15o Celsius level recommended for sorghum. However, even though establishment was poor for the intercropped plantings, it was higher for sole sorghum plantings. Wheat allelopathic effects may be involved. To avoid the temperature limitations of sorghum, sunflower was selected as an alternative intercrop in the later planting dates of Field Trial I and all dates for Field Trial II. Reasons for the poor establishment and yield of sunflowers in the earlier intercrop planting dates compared to sole plantings remain unknown but also may be related to allelopathic effects from intercropped wheat. Low soil temperature was not a factor affecting establishment Yields for planting dates were recorded in the intercropped sunflower treatments for Field Trial II and the optimal planting time for sunflowers in a wheat/sunflower relay intercrop was identified as when physiological maturity of the wheat had occurred. This may relate to the wheat crop stage. In Field Trial II, no significant differences in soil moisture were recorded between treatments from overall water use for the trial period. There were differences in water use between intercropped and sole cropped treatments for iii some rainfall events. Three rainfall events were chosen for closer study in each of the field trials conducted. Each event varied in the length and time as well as the duration and intensity of the rain that fell for the period. For the first rainfall period the moisture content of the first planting date of the sole summer treatment and to a lesser extent the second planting date of the same treatment increased, most likely due to wheat removal. In the third rainfall period the double cropped sunflower treatment with stubble tended to store less moisture and this may be due to the active crop growth at this time. It was evident in both field trials of the need for an effective weed control program in the intercrop plots. Weeds were controlled in wheel tracks by glyphosate sprays. Cultural methods may help but a herbicide suitable for both components of the intercrop would be very useful. A tractor was successfully modified to a 3 metre wheelspace and a clearance of 70 cm. This proved sufficient for planting the relay intercrop in Field Trial II without negatively affecting the yield of the standing crop. The row spacing of 18 cm for wheat in a 3 metre fixed bed and wheeltrack configuration assisted with guidance and interplanting of the relay crop. The relay crop was sown as single alternating rows.

The potential for relay intercropping and double cropping was assessed in field trials over three consecutive years at Gatton, Queensland. The rationale was to use controlled traffic technology to facilitate relay and double cropping and thus research a cropping system that could exploit late winter crop rainfall. In Field Trial I, grain sorghum and sunflower, broadacre crops already grown within the Southern and Darling Downs regions of Queensland and New South Wales were intercropped into wheat; sunflower was intercropped with wheat in Field Trial II. Sole summer plantings were made at the same time as intercrops were planted. The wheat crop was cut and stubble removed to facilitate this. Various planting dates (three for Field Trial I; four for Field Trial II) for the relayed summer crops were used to determine if an optimum planting time existed. Plant height, tiller number, light interception, grain yield, soil moisture and economic return were used as parameters to compare the intercrop with sole plantings in Field Trial I. Grain yield, soil moisture, rainfall infiltration and economic return were measured in Field Trial II. Research also involved the modification and testing of a tractor to carry out the sowing of the intercrop. In Field Trial I, light interception was shown to vary at different stages of the wheat crop and the use of these stages to determine optimum planting dates of the relay crop is suggested. In both trials, no differences were recorded in the grain yield between intercropped and sole cropped wheat treatments suggesting the trafficking of the plot did not affect the wheat. As neither sorghum or sunflower established as intercrops, competition was not a factor in affecting wheat yields. Moisture readings in both trials showed little change below a depth of 100 cm; however some treatment differences were present at shallower depths. In Field ii Trial I, sole summer sorghum, especially the first planting date, showed reduced water capture/ higher soil evaporation due to wheat removal initially and later transpiration loss due to crop growth and increased weed pressure. Sole wheat treatments showed increased moisture storage after harvest due to lack of water use by the crop and increased infiltration/reduced runoff due to stubble retention. Improved soil moisture recharge after rainfall events was apparent in double cropped treatments suggesting not only improved water utilisation but also improved capture and storage is possible within this system. Sorghum, commonly used throughout south eastern Queensland as a summer crop option, proved unsuitable for relay intercropping in Field Trial I for Planting Dates 1 and 2. Minimum soil temperatures for these plantings were marginal as they were close to the 15o Celsius level recommended for sorghum. However, even though establishment was poor for the intercropped plantings, it was higher for sole sorghum plantings. Wheat allelopathic effects may be involved. To avoid the temperature limitations of sorghum, sunflower was selected as an alternative intercrop in the later planting dates of Field Trial I and all dates for Field Trial II. Reasons for the poor establishment and yield of sunflowers in the earlier intercrop planting dates compared to sole plantings remain unknown but also may be related to allelopathic effects from intercropped wheat. Low soil temperature was not a factor affecting establishment Yields for planting dates were recorded in the intercropped sunflower treatments for Field Trial II and the optimal planting time for sunflowers in a wheat/sunflower relay intercrop was identified as when physiological maturity of the wheat had occurred. This may relate to the wheat crop stage. In Field Trial II, no significant differences in soil moisture were recorded between treatments from overall water use for the trial period. There were differences in water use between intercropped and sole cropped treatments for iii some rainfall events. Three rainfall events were chosen for closer study in each of the field trials conducted. Each event varied in the length and time as well as the duration and intensity of the rain that fell for the period. For the first rainfall period the moisture content of the first planting date of the sole summer treatment and to a lesser extent the second planting date of the same treatment increased, most likely due to wheat removal. In the third rainfall period the double cropped sunflower treatment with stubble tended to store less moisture and this may be due to the active crop growth at this time. It was evident in both field trials of the need for an effective weed control program in the intercrop plots. Weeds were controlled in wheel tracks by glyphosate sprays. Cultural methods may help but a herbicide suitable for both components of the intercrop would be very useful. A tractor was successfully modified to a 3 metre wheelspace and a clearance of 70 cm. This proved sufficient for planting the relay intercrop in Field Trial II without negatively affecting the yield of the standing crop. The row spacing of 18 cm for wheat in a 3 metre fixed bed and wheeltrack configuration assisted with guidance and interplanting of the relay crop. The relay crop was sown as single alternating rows.

The potential for relay intercropping and double cropping was assessed in field trials over three consecutive years at Gatton, Queensland. The rationale was to use controlled traffic technology to facilitate relay and double cropping and thus research a cropping system that could exploit late winter crop rainfall. In Field Trial I, grain sorghum and sunflower, broadacre crops already grown within the Southern and Darling Downs regions of Queensland and New South Wales were intercropped into wheat; sunflower was intercropped with wheat in Field Trial II. Sole summer plantings were made at the same time as intercrops were planted. The wheat crop was cut and stubble removed to facilitate this. Various planting dates (three for Field Trial I; four for Field Trial II) for the relayed summer crops were used to determine if an optimum planting time existed. Plant height, tiller number, light interception, grain yield, soil moisture and economic return were used as parameters to compare the intercrop with sole plantings in Field Trial I. Grain yield, soil moisture, rainfall infiltration and economic return were measured in Field Trial II. Research also involved the modification and testing of a tractor to carry out the sowing of the intercrop. In Field Trial I, light interception was shown to vary at different stages of the wheat crop and the use of these stages to determine optimum planting dates of the relay crop is suggested. In both trials, no differences were recorded in the grain yield between intercropped and sole cropped wheat treatments suggesting the trafficking of the plot did not affect the wheat. As neither sorghum or sunflower established as intercrops, competition was not a factor in affecting wheat yields. Moisture readings in both trials showed little change below a depth of 100 cm; however some treatment differences were present at shallower depths. In Field ii Trial I, sole summer sorghum, especially the first planting date, showed reduced water capture/ higher soil evaporation due to wheat removal initially and later transpiration loss due to crop growth and increased weed pressure. Sole wheat treatments showed increased moisture storage after harvest due to lack of water use by the crop and increased infiltration/reduced runoff due to stubble retention. Improved soil moisture recharge after rainfall events was apparent in double cropped treatments suggesting not only improved water utilisation but also improved capture and storage is possible within this system. Sorghum, commonly used throughout south eastern Queensland as a summer crop option, proved unsuitable for relay intercropping in Field Trial I for Planting Dates 1 and 2. Minimum soil temperatures for these plantings were marginal as they were close to the 15o Celsius level recommended for sorghum. However, even though establishment was poor for the intercropped plantings, it was higher for sole sorghum plantings. Wheat allelopathic effects may be involved. To avoid the temperature limitations of sorghum, sunflower was selected as an alternative intercrop in the later planting dates of Field Trial I and all dates for Field Trial II. Reasons for the poor establishment and yield of sunflowers in the earlier intercrop planting dates compared to sole plantings remain unknown but also may be related to allelopathic effects from intercropped wheat. Low soil temperature was not a factor affecting establishment Yields for planting dates were recorded in the intercropped sunflower treatments for Field Trial II and the optimal planting time for sunflowers in a wheat/sunflower relay intercrop was identified as when physiological maturity of the wheat had occurred. This may relate to the wheat crop stage. In Field Trial II, no significant differences in soil moisture were recorded between treatments from overall water use for the trial period. There were differences in water use between intercropped and sole cropped treatments for iii some rainfall events. Three rainfall events were chosen for closer study in each of the field trials conducted. Each event varied in the length and time as well as the duration and intensity of the rain that fell for the period. For the first rainfall period the moisture content of the first planting date of the sole summer treatment and to a lesser extent the second planting date of the same treatment increased, most likely due to wheat removal. In the third rainfall period the double cropped sunflower treatment with stubble tended to store less moisture and this may be due to the active crop growth at this time. It was evident in both field trials of the need for an effective weed control program in the intercrop plots. Weeds were controlled in wheel tracks by glyphosate sprays. Cultural methods may help but a herbicide suitable for both components of the intercrop would be very useful. A tractor was successfully modified to a 3 metre wheelspace and a clearance of 70 cm. This proved sufficient for planting the relay intercrop in Field Trial II without negatively affecting the yield of the standing crop. The row spacing of 18 cm for wheat in a 3 metre fixed bed and wheeltrack configuration assisted with guidance and interplanting of the relay crop. The relay crop was sown as single alternating rows.