The 'disableDnd' method is not provided in datagrid-dnd.js file, but extending it is easily.
$.extend($.fn.datagrid.methods,{
disableDnd: function(jq,index){
return jq.each(function(){
var target = this;
var opts = $(this).datagrid('options');
if (index != undefined){
var trs = opts.finder.getTr(this, index);
} else {
var trs = opts.finder.getTr(this, 0, 'allbody');
}
trs.draggable('disable');
});
}
});