A process for synthesis of ammonia including: producing an ammonia make-up synthesis gas in a front-end; raising the pressure of said make-up gas in a first compressor; feeding high-pressure make-up synthesis gas delivered by said first compressor to an ammonia synthesis loop; wherein said ammonia synthesis loop includes at least: a converter where ammonia is synthesized catalytically; a circulator, which is a compressor configured to maintain circulation in the loop and to deliver a feed gas, which includes the make-up synthesis gas, to said converter; a converter feed line from the circulator to the converter; a condensation section arranged downstream the synthesis section to receive an ammonia-containing gaseous product; a separation section wherein a condensate produced in said condensation section is separated into an ammonia liquid product and a gaseous recycle stream; a recycle line from the separation section to the suction of the circulator; wherein the ammonia synthesis loop has a full load condition corresponding to the processing of a nominal flow rate of make-up gas transferred from the front end to the synthesis loop, the process including controlling the loop at a partial load condition, wherein the flow rate of make-up gas transferred from the front end to the loop is smaller than said nominal flow rate, by means of: separating a gas stream from said converter feed line, at a point upstream of the converter, to form a bypass stream; reintroducing said bypass stream at the suction side of the circulator or into the ammonia synthesis loop at a point downstream of said separation section. producing an ammonia make-up synthesis gas in a front-end; raising the pressure of said make-up gas in a first compressor; feeding high-pressure make-up synthesis gas delivered by said first compressor to an ammonia synthesis loop; wherein said ammonia synthesis loop includes at least: a converter where ammonia is synthesized catalytically; a circulator, which is a compressor configured to maintain circulation in the loop and to deliver a feed gas, which includes the make-up synthesis gas, to said converter; a converter feed line from the circulator to the converter; a condensation section arranged downstream the synthesis section to receive an ammonia-containing gaseous product; a separation section wherein a condensate produced in said condensation section is separated into an ammonia liquid product and a gaseous recycle stream; a recycle line from the separation section to the suction of the circulator; wherein the ammonia synthesis loop has a full load condition corresponding to the processing of a nominal flow rate of make-up gas transferred from the front end to the synthesis loop, the process including controlling the loop at a partial load condition, wherein the flow rate of make-up gas transferred from the front end to the loop is smaller than said nominal flow rate, by means of: separating a gas stream from said converter feed line, at a point upstream of the converter, to form a bypass stream; reintroducing said bypass stream at the suction side of the circulator or into the ammonia synthesis loop at a point downstream of said separation section. a converter where ammonia is synthesized catalytically; a circulator, which is a compressor configured to maintain circulation in the loop and to deliver a feed gas, which includes the make-up synthesis gas, to said converter; a converter feed line from the circulator to the converter; a condensation section arranged downstream the synthesis section to receive an ammonia-containing gaseous product; a separation section wherein a condensate produced in said condensation section is separated into an ammonia liquid product and a gaseous recycle stream; a recycle line from the separation section to the suction of the circulator; wherein the ammonia synthesis loop has a full load condition corresponding to the processing of a nominal flow rate of make-up gas transferred from the front end to the synthesis loop, the process including controlling the loop at a partial load condition, wherein the flow rate of make-up gas transferred from the front end to the loop is smaller than said nominal flow rate, by means of: separating a gas stream from said converter feed line, at a point upstream of the converter, to form a bypass stream; reintroducing said bypass stream at the suction side of the circulator or into the ammonia synthesis loop at a point downstream of said separation section. separating a gas stream from said converter feed line, at a point upstream of the converter, to form a bypass stream; reintroducing said bypass stream at the suction side of the circulator or into the ammonia synthesis loop at a point downstream of said separation section.